Is it possible to report a player if you missed the button at the end of the game??
was playing ranked as a duo and left the screen to join my party

But id still like to report the player who suggested that i as an "illiterate n****" should hang myself before the klan finds me.....

any info on how i can report this would be much appreciated.

i would email riot, but im guessing theres probably an automated response to what would be an arrestable offence on the street...

You can submit a ticket to Riot Support. Best if you can provide a screenshot or some other evidence of it. But I can say from experince that you can expect a canned response, but that's because they can't share any other info (results) about other players.

A ranked game? I'm still not sure why threads like this end up in these forums. But yes, as above, contact player support with whatever evidence you have. If he is that toxic, he is probably in the Tribunal already, so look forward to that.