River advice

[chucky]

I know I didnt raise preflop, but villian wont fold if he hits anything (Anything meaning 2nd pair as well as two pair/set) so not much point in raising since I would still have river decision.
I have 9000 chips villian has 18k blinds 150/300.
In bb I get Kc3cKd4s. SB calls. all others folded.

Flop is Kh3h9s

I bet 500. villian calls

Turn is 4d.
I bet 1300. villian calls

River is 7d.

Villian bets 4200 (pot). Your advice?