Cool. That worked for me! Thank you very much, Boofo!
Some questions/comments about your solution:
You match "(.+\.)?". Any referer that will end with ".yoursite.com/" can still hotlink your images. So it's probably better to use "(www\.)?", unless you also want to allow subdomains.
Just a theoretical question: Is the dollar sign in the match pattern really needed? Because once the "*" is reached, it will match all the following characters. But I guess you need to tell the pattern where to start the search...
I don't know why my solution did not work. Maybe it was the pattern, maybe it was the NC,R,L...
Yes, that will match your site link with the www or without. As far as the pattern goes, my idea on that is, if it works, does it really matter? To be honest, I don't understand all the regex stuff yet. I am still learning.