How to add depth to a report?

Hey.

So I just had an extremely bad game - the kind that make you want to stop playing for an indeterminate amount of time.

And it was all caused by one player.

I don't think the report that I submitted fully did justice to the person's actions or allowed me enough depth, and I REALLY want to bring to light just how badly that one player has just affected me - and a teammate, not an opponent, no less.

Some context on the situation; I've been playing since roughly the start of season 2, and whilst I have both reported and been reported in the past, and I've had my fair share of short chat restrictions, I'm for the most part what I'd consider an honorable opponent; and I've never had a game where I've felt like such dirt afterwards because of one person.

How do I alert Riot to what happened in more depth? Or is the report tool the only way to bring to light a player's behaviour?

-Sir Half a Nut