Select the desired picture with the multi selector and press the i button.
Highlight [2.] and press
Choose a rating.
Rotate the main command dial to highlight the desired rating and press J to select. Choose from ratings of from zero to five stars, or select d to mark the picture as a candidate for later deletion.
Ratings can also be viewed in NX Studio.
Rating Pictures Using Camera Controls
If  has been assigned to a control using Custom Setting f3 [ ], pictures can be rated by holding the control and rotating the main command dial.