Question About Intentional Feeders

Everyone hates intentional feeders. They remove skill requirements for a win and put everyone on their team in a worse mood because of it. Thankfully, the report option does help weed these players out. I had a game less than 30 minutes ago where my team destroyed the enemy team in all lanes. The enemy thresh/cait bot lane were pretty tilted and the thresh referred to her as having "down syndrome", being clearly on hard tilt. I requeue and I get both of them in the same role. Interesting, maybe premade? Regardless, the thresh in the chat which I have saved, says that he is going to intentionally feed and takes support veigar with cleanse/clarity. My question is - given that I have him admitting to this and linking a URL to buying a new league of legends account, can I report this player in anyway to riot here in the forums for real punishment?

Thanks for reading and best of luck, summoners!\

Note: someone dodged before the game began, otherwise I'd clearly report him post-game.