Player Inting in Game During Promos

Hello all! I was duoing with a friend of mine and a player recently inted for an improper lane push losing my friends promos and causing everyone to lose LP. I don't know if I should leave a summoner name on here but it was a mid tier Silver match with the inter being Plat. 3 last season. If a Riot employee responds I am willing to disclose the summoners name and video evidence as well. This is the first inter I have really experienced and don't know if this is the board to report since it wasn't just a bad game on his part. The inting happened at around 8min. into the game with his lane going well and the inter being 1-0-0 with first blood. The enemy team agreed it was immature and the game ended in a loss for us of course. I don't like to rely on others promises of reports so I would like to see this through since I don't believe 2 reports from my friend and I will correct this. Let me know what course of action to take if this is not the correct one :) Thanks, AzuraEM