Make sure to use your king! When all else is equal, the side with the more active king will get the upper hand. If you're unsure how to evaluate a knight endgame, try to see which king is closer to the center or queenside -- the closer king will be able to contribute to the action first.
If you are reading this instead of viewing a chess puzzle or game, then you must enable JavaScript on this website.
[Event "rated untimed match"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "White player"]
[Black "Black player"]
[Result "*"]
[BlackElo "0"]
[FEN "R7/8/8/8/4k3/8/8/7K w - - 0 1"]
[SetUp "1"]
[TimeControl "0"]
[WhiteElo "0"]
{ Both the white king and rook must work together to checkmate the black
king. } 1. Ra5 { Step 1: Push the black king to any side of the board.
Naturally, black will resist every step of the way.|White fences off half of
the board with this move. } 1... Kd4 2. Kg2 { Getting the white king involved! } 2... Ke4 3. Kg3 Kd4 4. Kf3 Kc4 5. Ke3 Kb4 6. Rh5 { Protect your rook while maintaining
the a5-h5 fence that black cannot cross. } 6... Kc4 7. Rg5 { A simple waiting move
that forces black to move toward one side of the board or another. } 7... Kc3 8. Rg4 { Moving the fence to force black further toward a side of the board. } 8... Kc2 9. Rc4+ Kb3 10. Kd3 Kb2 11. Rb4+ Ka3 12. Kc3 { Now for step 2. Achieve king
opposition with white to move. } 12... Ka2 13. Kc2 Ka3 14. Rf4 { Another waiting move
that forces black to move into opposition. } 14... Ka2 { Opposition is achieved. Now
for step 3. Checkmate. } 15. Ra4# *