It isn't completely obvious where the torrc file needs to reside on a Mac (say, 10.6). In Settings->Advanced, it appears to be in Applications/TorBrowser_en-US/Library/Vidalia/torrc. But there is also a USER/.tor directory.
Also, FWIW, whenever I use the Tor configuration file editor to try to change that file (for example, adding an ExitNodes line), I get a 'Error at line 1:""' error message. I seem to be unable to successfully edit that file.
I'm confused. On a Mac, if I want to add an ExitNodes line, where exactly does it go and how do I get it there?