I'm not too sure about the fold to be honest. The only better hand you have there is KK, and AdKd, he can be shoving with Axhh and the pot is not that small anymore... If he ever spazzes, does it with a worst K that he feels he needs to protect from a flush draw etc don't think you're doing that bad. BUT I very rarely play with players that limp so take my opinion with a grain of salt.

In game I thought I need to raise to get in more money against worse Kx and to not let flush draws and gutshots get such a great price

Your raise on the flop was a bad mistake and your reasoning was faulty. First of all, you have several streets to get in more money vs a worse king. Secondly, the board is very dry. You don’t really need protection. True, there is a flush draw, but you can’t let that scare you. Thirdly, when you raise on a dry board like this, the only thing you’ll achieve is that your opponents fold all the hands you dominate, and continue with the ones that crush you. Fourthly, in a multi-way pot the value of a single pair goes down significantly, and looking to shovel money in, is not a winning strategy. The correct play would have been to call, planning to call down barring a bad run out.

I like the flop raise. When they limp they have a wide range and indicate that they are fish. Then they donk and indicate once more they are bad. So if they have some sort of flush draw or a small piece of the board they will still pay you off. Just get more money in against fish. No need to play balanced here.

I would call the all in. Fish will be fish. We block K6s, K2s (which surprisingly they could have). We beat other Kx. And we are ahead of flushdraws. His value range is super thin with lots of potential bluffs or weaker hands from a fishes wide range.

Thanks for the feedback everyone. I looked back at the hand at he had KQo no heart for the shove and the middle player had 33 with a heart so it seems folding was a significant mistake. I think I feel better about the raise as well.