I always thought, the "correct" way of doing this was the other way around: the RSS reader would implement ActivityPub so you could "toot" from within you RSS client. It would perhaps attempt to collect other "toot"s about the same link, facilitating a discussion (and keeping everything at one place). But I think this is the next best thing, especially for those feeds you tend to share on the social networks (I don't think it's feasible to reproduce the RSS reader following with this).