I wanna know if I can report per screenshot

I really have it with those trolls in the last week. I have had at least 6 of those people 4 of which picked and trolled with soraka toplane after kalye got banned and now they even anounce the lose in the lobby... and there is no way to report one of those people.... What can I do? Should I just screenshot and mail it to riot support or is there no point trying? I left the draft because I didnt want to lose 17 points.