This was a pretty easy fold for me. Many people do not fully respect an early position raise, especially since it was a pretty decent player. Just because this hand turned out alright for you, KTs is not that great of a hand and most likely you are way behind. I know it wasn't much more to see the flop, but what happens if you get a piece of the flop, even if a K comes out. He could have KQ, AK, or even KJ (less likely). So most times this is a pretty easy fold for me as I would like to pick a better spot to play. You are also out of position.