Core on Mac OSX 10.3

[rosie]

I recently installed Rebol on a friend’s Mac OSX 10.3. The console comes up, and it responded to print "Hello" with Hello, ergo it's alive.

However, the system won’t run r files. I’m not a Mac person, so I have 2 questions:

1 why isn’t the file extension automatically recognised by the Mac?
2 what to do with the following error message - Access error cannot open /users/fredsmith/setup.r

Can someone enlighten me?