Um... I appreciate your dedication to being a salty mofo, but more likely what will happen is Riot will not notice or care... but eventually you might catch a ban for it if it happens enough. People make entire accounts JUST to feed, and it takes them WAY longer than it really should to get caught... I highly doubt they're gonna notice you doing it when you're autofilled if that's the only time you do it. I also highly doubt Riot gives half a shit about one person's crusade to make a point. If you do it enough you'll get banned eventually.
But let me posit this question to you, my salty friend. Why bother? I mean, your reasoning doesn't seem to track. If you are angry about being autofilled in ranked it must be because you want to improve in rank and you feel autofilling you gimps your chances. I mean, obviously you take ranked seriously right? So why tank your own ranking int feeding in a role you're not good at, but might be able to play juuuuust well enough to win? I mean, if you care about your rank why wouldn't you attempt to win, even if you're pissed at being at a disadvantage. One extra win, even one you get carried in, makes you higher ranked overall. If you lose 80% of the games you're autofilled in, that is still a significant number of autofilled games you'd win if you gave even HALF a shit and just DIDN'T feed. Or alternately, if you are only playing to have fun and you only enjoy your normal roles... why play ranked at all? Just to shit on people's games if you get autofilled? You are slowly but surely sabotaging your own ranking by deciding to be a douche and feed on games you get autofilled. Seems like your attitude might be a bigger part of your problem than autofill. I mean... protesting something that hurts your rank by... hurting your rank is like protesting a poorly lit staircase that you trip on sometimes by intentionally throwing yourself down the stairs headfirst.
Honestly, you just sound pretty toxic to me. My suggestion is this... don't feed when you're autofilled. Feed EVERY game. Anytime someone speaks in chat. Anytime someone bans a champ you like or says ANYTHING to you. Flame EVERYONE who dies, and throw around sexist and racist language at every opportunity. Be sure to pepper in some REALLY inappropriate suggestions that other players should off themselves, call EVERYONE trash and to say "Report me, I don't care" while spamming pings EVERY game.
That will get you taken out of the player pool as quickly as possible, I think. It's what's best for everyone.