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Exhibit 10.43

SEPARATION AGREEMENT AND COMPLETE RELEASE

This Separation Agreement and Complete Release (this “Agreement”) is made this 28^th day of January, by Timothy P. Beattie (“Employee”), Rex Energy Corporation (“Rex Energy”) and Rex Energy Operating Corp. (collectively, Rex Energy, Rex Energy Operating Corp. and their successors are referred to as the “Company”).

In consideration of the mutual agreements described below, the payments to Employee and other good and valuable consideration, the receipt and sufficiency of which the parties acknowledge, Employee and the Company agree as follows:

Employee’s employment with the Company will terminate as of January 28, 2011 (the “Separation Date”). Employee hereby tenders his resignation from the Company and from all officer, employee and committee positions, of the Company, its subsidiaries and its affiliates, effective immediately upon execution of this Agreement.

In consideration for the covenants, release and agreements under this Agreement, the Company shall pay or provide the following:

Employee acknowledges that Employee is not otherwise entitled to the separation pay set forth in Section 2 of this Agreement and that Employee is receiving the separation pay solely in exchange for the promises contained in this Agreement. Employee acknowledges that the Company has no obligation to provide severance pay to an employee whose employment is terminated under the circumstances in which Employee’s employment has been terminated.

Employee shall not, without the prior written consent of the Company or as may otherwise be required by law or legal process, communicate or divulge any such trade secrets, information, knowledge or data to anyone other than the Company and those designated by the Company. Employee agrees to return all Confidential Information, including all photocopies, extracts and summaries thereof, and any such information stored electronically on tapes, computer disks or in any other manner, to the Company upon the Separation Date.

For purposes of this Agreement, “Restricted Territory” means anywhere within a two-mile radius of any area of mutual interest, evidenced by a written contractual obligation, of the Company or its subsidiaries or any oil or gas property in which the Company or any of its subsidiaries has an interest as of the Separation Date. With the Company’s prior written consent, which will not be unreasonably withheld, the Employee may work for a company or employer that is competitive with the Company so long as the Company receives reasonable written assurances from Employee and his new employer that employee will not work in areas competitive with the Company or divulge Confidential Information. For purposes of this Agreement, “Competition” by Employee means Employee’s engaging in, or otherwise directly or indirectly being employed by or acting as a consultant or lender to, or being a director, officer, employee, principal, agent, stockholder, member, owner or partner of, or permitting his name to be used in connection with the activities of any other business or organization which competes, directly or indirectly, with the business of the Company or its subsidiaries as the same shall be constituted at any time before the Separation Date.

In consideration of the separation pay set forth in Section 2 of this Agreement, as well as the other benefits that this Agreement provides, Employee (on Employee’s own behalf and on behalf of Employee’s heirs and other legal representatives and assigns) releases the Company, its subsidiaries and affiliates, and employees, officers, directors, representatives, attorneys and agents of any of them, and their respective successors, predecessors and assigns, from all legally waivable claims, charges, costs, attorney fees or demands Employee may have, including without limitation claims based on Employee’s employment with the Company or the cessation of that employment, accruing through the date

Employee executes this Agreement. This includes, but is not limited to, a release of any rights or claims Employee may have under the following (as each may be amended through the date of this Agreement):

This also includes a release by Employee of any claims for wrongful discharge or any tort, contract or common law claims, including claims for past or future loss of pay or benefits, expenses, damages for pain and suffering, mental anguish or emotional distress damages, liquidated damages, punitive damages, compensatory damages, attorney’s fees, interest, court costs, physical or mental injury, damage to reputation, and any other injury, loss, damage or expense or any other legal or equitable remedy of any kind whatsoever. This release covers both claims that Employee knows about and those he may not know about. This Agreement does not affect Employee’s ability to file a charge with or participate in any investigation or proceeding by the Equal Employment Opportunity Commission, although Employee agrees and understands that he will not receive any personal relief from any such charge.

Employee waives any right he may have under any dispute resolution process of the Company to arbitrate the claims which Employee has released by entering into this Agreement. This release does not include, however, a release of the following:

Employee promises never to file a lawsuit asserting any claims that are released in Section 6. If Employee or anyone else on Employee’s behalf files a lawsuit asserting any of these claims, Employee waives his right to receive any

monetary award, settlement proceeds, or reinstatement as an employee of the Company. Employee agrees that this Agreement is a complete and total bar to his reemployment or to recovery of any money from the Company resulting from any lawsuit, charge or complaint raising any claims that are released in Section 6. Employee understands that he is not waiving the right to test the knowing and voluntary nature of this release agreement in court.

Employee understands that pursuant to federal law any frivolous or legally unwarranted challenge to the validity of this release agreement may result in payment to the Company of its attorney’s fees and other legal costs incurred defending the validity of this Agreement.

The Company makes this Agreement to avoid the cost of defending against any possible lawsuit. By making this Agreement, the Company does not admit that it has done anything wrong.

This Agreement does not waive or release any rights or claims that Employee may have under ADEA that arise after the date Employee signs this Agreement.

Employee acknowledges that the Company has afforded Employee an opportunity to engage and consult with legal counsel of Employee’s choosing in connection with the negotiation and entering into of this Agreement, and that he has, in fact, consulted with legal counsel prior to entering into this Agreement.

Employee understands that Employee has up to 21 days to review and consider this Agreement, which Employee acknowledges is a reasonable amount of time to review and consider the Agreement. If Employee should elect to sign this Agreement in less than 21 days, Employee expressly waives Employee’s right to the full 21-day period to review and consider this Agreement. Employee further understands that Employee may revoke the Agreement at any time during the seven-day period following Employee’s signing of the Agreement. Employee further understands that if Employee fails to sign the Agreement or revokes the Agreement, the Company shall have no obligation to provide the separation pay set forth in Section 2 of this Agreement, as well as the other benefits described in this Agreement, to Employee. Revocation shall be in writing and shall be effective upon timely receipt by Daniel J. Churay, Chief Executive Officer of the Company.

Employee acknowledges that, whether or not this Agreement becomes effective, Employee’s employment with the Company will end on the Separation Date.

This Agreement is made in the Commonwealth of Pennsylvania and is governed by the laws of Pennsylvania, excluding its law of conflicts of law, and any action to enforce this Agreement shall be brought in the Court of Common Pleas of Centre County, Pennsylvania, or the United States District Court for the Middle District of Pennsylvania.

This Agreement is binding on the representatives, heirs, successors and assigns of Employee and the Company.

This Agreement cannot be changed, modified, or amended in any respect except by written instrument that Employee and an officer of the Company sign.

The provisions of this Agreement are severable, that is, if any part of it is found to be invalid or unenforceable, the other parts will remain valid and enforceable and shall be construed to the greatest extent possible to be enforceable as written.

Employee has returned or will immediately return to the Company all Company information and related reports, files, memoranda and records, computer disks or other storage media, physical or personal property which Employee was provided during his employment, including credit cards, card key passes, door and file keys, computers, cellular phone, pagers or leased vehicle. Employee has returned or will immediately return to the Company all such information and property that Employee received or prepared or helped prepare in connection with his employment, and Employee has not retained or will not retain any copies, duplicates, reproductions or excerpts thereof.

After the Separation Date, to ensure a smooth transition from Employee’s employment with the Company, Employee shall provide reasonable assistance to and cooperation with Company during the Separation Pay Period in connection with any Company matters concerning which Employee had knowledge or responsibility while the Company employed Employee. Whether during or after the Separation Pay Period, reasonable out-of-pocket expenses related to such assistance will be reimbursed by the Company, if the Company’s approval is obtained in advance. The Company’s request for cooperation shall reasonably accommodate Employee’s obligations to any new employers or any medical treatment that Employee may be taking.

If Employee dies prior to receipt of the payments that this Agreement provides, Employee’s estate shall be entitled to receive any remaining payments to the extent that Section 2 of this Agreement so provides (and subject to the other terms and conditions of this Agreement).

The headings of this Agreement are for convenience only and shall not affect the interpretation or construction of this Agreement. When used in this Agreement, unless the context expressly requires the contrary, references to the singular shall include the plural, and vice versa; references to the masculine shall include the feminine and neuter, and vice versa; references to “Sections” shall mean the sections and subsections of this Agreement; references to “including” mean “including, without limitation;” and references to the “parties” mean the Company and Employee and to a “party” mean either one of them.

If there is any inconsistency between this Agreement and any summary of this Agreement, such as a summary provided in a document to Employee, the terms and conditions of this Agreement shall control and the summary shall not be used to interpret or construe this Agreement.

This is the entire Agreement between Employee and the Company and supersedes all prior understandings, whether oral or written, between the Company and Employee. The Company has made no promises to Employee other than those in this Agreement.

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EMPLOYEE ACKNOWLEDGES THAT HE HAS READ THIS AGREEMENT, UNDERSTANDS IT AND IS VOLUNTARILY ENTERING INTO THIS AGREEMENT.

PLEASE READ THIS AGREEMENT CAREFULLY. IT CONTAINS A RELEASE OF ALL KNOWN AND UNKNOWN CLAIMS.