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.