For some reason Google Reader / Reeder can be pretty difficult to subscribe to feeds with. You click the “Add a Subscription” button, enter in the feed URL, and it kicks back a “feed not found” error.

Hello, I didn’t want to search, I gave you the URL of the stupid feed.

It seems that changing the prefix of the URL from http:// to feed:// will force it to treat what you entered as a URL instead of a search term.