I think if you were able to attach a screenshot it would help clean up community. Many toxic players flame in beginning or at end of game, if you were able to attach a screen shot showing their vileness it would help ban them.
Ok buuuut... You could just note to check the pre and post game chats. Works just as well.
I do think this could be a good or bad idea, as you can easily leave out the parts where you are feeding/being toxic. lets stick to chat logs for now maybe
File a Riot Support Ticket. You can attach links there like screenshots.
I personally use Snipping Tool, something included on my computer, to just take quick screenshots of the toxic behavior, and then link to imgur post in the report.
I also post it under a ticket for a report, along with relevant information or context.
