Its no Sacrifice

I rarely have a chance to play this sort of move, probably because my games either end earlier, or the endganes are much closer.
Anyway. here we are.

The game is lost for Black, but gamely, he plays on, bringing the king closer, and finally, blocking the f-pawn with the knight, and leaving the White Rook blocking his own g-pawn.

Job done ? Some sort of parity ?

No, actually, a win for White....

White to play and win

Highlight for solution , if you should need it  ! [  Rd8+ , checks and clears the queening square. Obvious once you've seen it before, or are a genius : for me, its the former ! ]