Kenwood KDC-X997 Manual page 53

Basic operations
Stop/Pause and play a song
Press and hold [1/6].
Skip track (Custom station)
Press [F].
Thumbs up (Custom station)
Press [R] button.
Thumbs down (Custom station)
Press [S] button.
Adding to favorite stations (Live station)
Press and hold [R].
Creating a custom station name
Press and hold [Control] knob.
A custom station name is created according to the current song information.