Excluding URLs & regex

(from github.com/looper976)
I am trying to exclude the crawling of web results that look like the following: (feed)

http://site.net/category/reset/build/feed
http://site.net/category/reset/build/feed/

But I don’t want to exclude pages that have the word feed in the middle of the URL:

http://site.net/category/feeding/build/

I am trying to use something like this /feed$ but it does not appear to be working. Do I have to have the regex match the entire URL or just the specific pattern I am after?

Thanks,

(from github.com/marevol)
Did you try .*/feed/?

(from github.com/looper976)
That works, thanks!