If the ball hits a finger and paddle together and returns to opponent’s table, is it correct of foul?
If you hit the ball with your finger (or any part of you hand below the wrist), and it goes over the net, then it is allowed. The rule in the ITTF handbook is as follows…
2.57 – A player strikes the ball if he or she touches it in play with his or her racket, held in the hand, or with his or her racket hand below the wrist.
A double hit is not allowed. If you were to hit the ball with your hand and then racket, this would be a foul. But I don’t recall this ever happening when I have played.
Most likely a player will unintentionally hit the ball with a finger, which will then create a disruptive effect on the ball – change of spin, speed or direction. This is tough luck. Usually a player will apologise for an unintentional finger shot.