Rijk van Geijtenbeek saw the previous post and let us how to do the same thing with Opera 7.21 and higher. Just open the URL below in Opera:
http://people.opera.com/rijk/opera/ini/menu/feeddemon-in-linkcontextmenu.ini
This will add a “Send to FeedDemon” item to Opera’s context menu which enables passing the URL of an RSS feed to FeedDemon.
Note for Opera customizers: this is the relevant line to add to the active menu.ini file:
Item, "Send to FeedDemon" = Execute program, "feeddemon","%l"