In live, you can play for time. If that wasn't an option, I would have resigned too.
What should I have done?
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1. c3, Rxb2 then follow up with either capturing the a pawn or threatening to with Ra2 if he moves it up. You win two pawns and create a passed pawn on the a file. You lose your 7th rank pawn, but that is lost anyway. It's probably still lost for you- knight down- but you should have a chance.
You are as dead as a doornail my friend, you did well to lose. 
Hello.
I was on LIVE and, after 40 moves, got this endgame. In six moves I would resign. Could I have won? What should I have done? Thanks!