Depends what you mean by feeder.
If you mean the person who got cc locked to death 10 times or who got 3v1 10 times because no one called MIA, no, that's not their fault though I may say "just play safe, we have late game" to try and keep morale up.
If you mean the person who died to their laner 10 times and are still trying to 1v1 like they are even, I may request they "play safer and farm, we win teamfights", but they don't deserve to be raged at.
If you mean the person who goes 0/3 and then sells all items, buys 6 tears, and stands in the enemy base spamming taunt while the enemy free farms them, then I at least am going to call for the team to report them while we try to win this 4v5.
No one deserves to be raged at in general. It's a game and while I want to win, I'm not going to scream at someone for playing badly. However, if I offer advice to my Leblanc vs Annie who's died 3 times saying, "maybe rush an abyssal scepter since it's good on Lb anyway and will help counter Annie's burst some," and get told "stfu noobs or I'll afk," then honestly there is nothing more I can do to try and help save this person from ragers since they are contributing to it.
Same as if we burst bot lanes summs and chunk them to half health then call for the jungler who's doing red to come gank since they are still in lane only to have that request ignored or, better yet, the jungler clears raptors and golems before wandering down at half health right after our adc backs. I don't deserve to rage at them because of that, but I'm hard pressed to support their actions when they complain "gg, we never group" as 4 of us sit mid under inhib tower trying to waveclear and the jungler dies at the enemy red.