lucy24 - 8:08 pm on Apr 19, 2013 (gmt 0)
Color me confused. Your RewriteCond says "If the query string does NOT contain 'format=feed' then strip the query and redirect to /rss.feed."
If you use the [R] flag then your rule creates a redirect whether or not you've included the protocol-plus-domain-- but it's a sloppy redirect because you're not canonicalizing the hostname. Conversely if you do include the protocol-plus-domain then the rule becomes a redirect even if you don't use the [R] flag. Unless you've instead used the [P] flag, but let's not make it more complicated than it needs to be.
Eeuw. Is that supposed to be the "before" or "after" form? I guess it has to be what the user sees, because a real file doesn't end in / alone.
Better backtrack a bit and explain in English what you want to do. What the user is supposed to see; where the content lives.
Any new rules you make need to come before the CMS rules of the same type. Your redirects come before their redirects; your rewrites come before their rewrites. Exceptions exist, but we'll deal with those if-and-when they arise.
Rules involving redirects and query strings almost always need a preceding RewriteCond looking at THE_REQUEST so you don't go around in circles. And, as always, make sure your own internal links point to the URL you want people to see. Redirects are for outdated links and bookmarks coming from outside. And for search engines with long memories.