I don't own a Mac, so can't really say for certain, but I think this is a path to find your save files:
~/Library/RenPy/game_directory
To access the above path:
Open up a Finder window
Press COMMAND + SHIFT + G
Paste/enter the path (~/Library/RenPy/game_directory) into the text field and hit Go
Hopefully that helps! And thanks so much for playing.