Lost endgame with rook vs. knight?

I was black in this game.  I held up well, but my opponent blundered (I think) toward the end and I was up a rook vs. knight, with almost even pawns, but I ended up losing.  How could I have played differently not to lose an endgame like that?

This game really started to get out of hand thanks to a simple tactical oversight.  With that in mind, I would suggest just looking out for those tactics.  You'd be surprised when you consider just how important tactics play in the endgame.  Where I think you really became lost, however, was actually, move 26 Rb8?, which allowed white to capture C4 with check.  This leaves your opponent, down an exchange, with a strong queenside majority just waiting to start rolling, while you toil with a weak d pawn.  Again, look out for tactics, you would have winning safely had you continued with C5! after which white's b2 pawn quickly becomes untenable.

In addition, in the moves after that, you made your position more and more difficult by withdrawing your king from the action, after which white's queenside pawns really start to dominate.  Remember: king position becomes incredibly important in the endgame, and you allowed your opponent to completely dictate that battle as well.

Well, you look okay through white's 25th move. White is down the exchange, but has a pawn in compensation. You are winning, I think, but you need to tread carefully. For instance, you immediately fail to defend or move the c-pawn, and let white just take it. And then you allow white to march his king to the center of the board and take your d-pawn uncontested. White is up three pawns, one passed, is about to put the a-pawn in jepoardy, and is completely winning. Meanwhile, it doesn't appear to me that you don't know how to maximize the value of your rook, as in the space of eight moves, you shuffle it from a8 to e8 to b8 to h8. I don't see a consistent plan in any of those moves, and in fact, the most efficient use of the rook is to place it on e8, cutting the white king off from the queenside. Your comment on move 40 that you were "getting into trouble" is quite the understatement, as you were completely lost. White played this endgame pretty well, I think. Notice at move 39 how his knight cut off the rook's access to b2 and f2. This guy knew what he was doing. You were up the exchange, but he managed to make your rook completely impotent, and deserved to win.

Fiveofswords: well, technically, the ending was originally a minor piece + 1 pawn vs. a rook, which usually favors the rook.