How do I report this troll?

Just got into champ select and had this guy: http://imgur.com/a/eVU4R

Someone dodged thankfully.

I look at Riot website and it says they cant be punished unless reported from the in-client. https://support.riotgames.com/hc/en-us/articles/201752884-Reporting-a-Player

Is there a way to do this other than the post-game screen?