anyone do this often in their game?

PokerStars Pot-Limit Omaha High, $0.50 BB (9 handed)

UTG+1 ($37.95)
MP1 ($50.20)
Hero ($77.25)
MP3 ($13)
CO ($31.50)
Button ($34)
SB ($55.05)
BB ($9.65)
UTG ($50)

Preflop: Hero is MP2 with , , , .
UTG calls $0.50, UTG+1 calls $0.50, MP1 calls $0.50, Hero calls $0.50, MP3 calls $0.50, CO calls $0.50, 1 fold, SB completes, BB checks.

Flop: ($4) , , (8 players)
SB checks, BB checks, UTG checks, UTG+1 checks, MP1 checks, Hero checks, MP3 checks, CO checks.

Turn: ($4) (8 players)
SB checks, BB bets $2.5, UTG calls $2.50, UTG+1 folds, MP1 folds, Hero calls $2.50, MP3 folds, CO folds, SB calls $2.50.

River: ($14) (4 players)
SB checks, BB bets $6.65 (All-In), UTG folds, Hero raises to $18, SB folds.

Final Pot: $38.65

I hit the nuts on the river. If i raise, they know i have it so should i just call and hope for an overcall or even someone with a lower flush raising? anyone do this frequently?

With 2 others to act I think the overcalls is probably your best bet. If #3 calls then #4 will be getting great pot odds and you'll win 2 extra bets. If somebody made a straight or lower flush then they may even raise. If it was just one guy I'd might min-raise instead.

Yes, this is definitely a bad spot to raise. Calling is far superior unless you're up against the absolute worst of players.

That said, your hand has the classic "no call feature" of a nut flush hand - that is, you also hold the second nut flush card (the K) so after a bet and a call on the river it's hard to even see a reasonable player calling you with the next best flush (the T).