Show a "Mark as unread" button at the top of the RSS article

when scanning the new articles, sometimes I end up opening an article that I decide to read later, which is often the case for long articles. I then want to mark the item as unread to avoid it gets lost, but to do so I have to scroll down to the end of the article, which may be several screens long.
Having an easily accessible "mark as unread" button at the top (say next to the posting date/time) would really make life easier (at least for me).