According to CoronaSDK's official instructions, the Ad Hoc Provisioning Profile File is in this location:
/Users/(your user)/Library/MobileDevice/Provisioning Profiles/
However, you may not have access to this particular folder.
Unhide the folder
Mac OSX hides the ~/Library folder by default. To remedy this, open a new Terminal app window and run:
chflags nohidden ~/Library/
If you still experience issues after this please contact our support staff.