@george64
1.Rf5!! is the only winning move, otherwise the game would fiddle out in a draw.
If black takes with the pawn, 1.-g:f5 then 2.Nf6#
If black takes with the N, 1.-Nf5 then 2.Nf6# once again
If black takes it with the K, 1.-Kf5 then 2.Ne7+ followed by taking the rook on c8
If black doesn't take, 2.Rg5 checkmate next.