Reporting Players Outside of Postgame Screen

I'm wondering if there is any system currently in place to report players, other than on the postgame menu.

I just finished a game where my team was behind the entire game, and while morale was not good it was not to the point where I would have reported anyone based on their in-game messages. However, one of my teammates friend requested me after the game. I knew where this was likely going but decided to play along.

This player then sent numerous messages that, if received in-game, would have been report-worthy. I now find myself wanting this person to go through the tribunal process but feel that I am too late.

I have a screenshot of the summoner name and messages I received. I could submit a ticket through the normal Riot support screen but none of the topics seem relevant to my problem. So, does anyone know how I can proceed from here? I'm sure that the overwhelming majority of reports are taken care of on the postgame screen, but there should also be some method of letting Riot know about people who act in the manner of the player above.

Thanks for your time.