I think that Ctrl-R maybe should map to "refresh" when viewing a feed article, like it does with the browser. I don't know of any mechanism to "reply" to an RSS feed (but perhaps I'm just ignorant), and so it seems like it wouldn't conflict. If it does conflict, at least a context menu item if not another shortcut would be helpful. Of course... there's the bigger dream of making the feed window more of a browser in general rather than popping out to Firefox when you click on links and stuff... but that's for another bug.
this can be accomplished by selecting View-Feed Message Body As- and then either default format (if already checked, and default is web page, it will reload) or web page.