i am having the same issue. Managed to get by under the church when the pig appears just by legging it past him after about 30 attempts. Now under the pistons same issue when he pops back up. My specs are fine. Downloaded this off Apple app store a few days ago.
Process: AmnesiaAMFP [1152]
Path: /Applications/AmnesiaAMFP.app/Contents/Resources/AmnesiaAMFP.app/Contents/MacOS/AmnesiaAMFP
Identifier: com.frictionalgames.AMFPLauncher-game
Version: 1.0.2 (1.0.2)
Code Type: X86 (Native)
Parent Process: ??? [1]
Responsible: AmnesiaAMFP [1152]
User ID: 501
Date/Time: 2014-06-05 19:32:38.395 +0100
OS Version: Mac OS X 10.9.3 (13D65)
Report Version: 11
Anonymous UUID: C6CCD42A-B1E0-447B-0152-E1EF289C9996
Sleep/Wake UUID: A17A2158-F07D-4BA7-849C-66BB8A73F43D
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Application Specific Information:
abort() called
*** error for object 0x1b1b3460: pointer being freed was not allocated