Bluff the river here?

[ras52]

Live $100 tourney, effective stacks > 100BB. All decent players, Villain and I are the ones who have played the least hands so far, and we have no prior history.

One EP/MP limper, I limp along from LP with K[img]/images/graemlins/spade.gif[/img]4[img]/images/graemlins/spade.gif[/img], four players see the flop of 3-8-9 with one spade. Checked to me, I check. Turn 9[img]/images/graemlins/spade.gif[/img], giving me a flush draw. Checked to me, I bet around 2/3 the pot, get one caller (I don't remember if Villain is blind or first limper). River is a brick, Villain checks.

I don't think I can convincingly represent a 9 here as I didn't bet the flop. Neither did he, so I suppose he's paired the 3 or 8 or was drawing with JT or X[img]/images/graemlins/spade.gif[/img]X[img]/images/graemlins/spade.gif[/img], so I can only beat the straight draw and ace-less flush draw. My turn semi-bluff didn't work and I didn't improve - check behind or bluff? Is it even a good idea to semi-bluff into 3 opponents with a non-nut draw?