And if it can help,
we can see the chatlogs for every Skial server, so actually there is no special need for screenshots of text spamming.
However when it is micspamming, you can record a demo and upload it for the admins to review.

Additionally, admins need the Steam ID in the form of steam_xxxxxxxxxx to file a ban. You can get that Steam ID for them (to make it easier for them) by searching the name of the reported on the HLStats page and copying the Steam ID. In game you can type 'status' in the console to get a list with all Steam ID's.

Hope this will help you for next time. ;)