Exceedingly Tough Rook and Pawn Ending
This is a tough ending, bordering on inhuman. It is derived from a longer study that Gonzalez created, but this position is likely the one from which he constructed the composition working backwards. There are a few natural looking moves that only draw with best play- you really should start there and understand how black draws afterwards- then try to find the winning move for white.
8/6P1/2kp3K/8/4R2p/6r1/8/8 w - - 0 1