Exhibit 99 Form 3 Joint Filer Information Name: EnCap Energy Capital Fund VIII, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Designated Filer: Eclipse Resources Holdings, L.P. Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 06/24/2014 Signature: EnCap Energy Capital Fund VIII, L.P. By: EnCap Equity Fund VIII GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C, its general partner By: /s/ D. Martin Phillips, Sr. Managing Director --------------------------------------------- Date: 06/26/2014 Name: EnCap Energy Capital Fund VIII Co-Investors, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Designated Filer: Eclipse Resources Holdings, L.P. Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 06/24/2014 Signature: EnCap Energy Capital Fund VIII Co-Investors, L.P. By: EnCap Equity Fund VIII GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C, its general partner, By: /s/ D. Martin Phillips, Sr. Managing Director --------------------------------------------- Date: 06/26/2014 Name: EnCap Energy Capital Fund IX, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Designated Filer: Eclipse Resources Holdings, L.P. Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 06/24/2014 Signature: EnCap Energy Capital Fund IX, L.P. By: EnCap Equity Fund IX GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C, its general partner By: /s/ D. Martin Phillips, Sr. Managing Director --------------------------------------------- Date: 06/26/2014 Name: EnCap Investments GP, L.L.C. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Designated Filer: Eclipse Resources Holdings, L.P. Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 06/24/2014 Signature: EnCap Investments GP, L.L.C. By: /s/ D. Martin Phillips, Sr. Managing Director --------------------------------------------- Date: 06/26/2014