Using an Airturn pedal
Then make sure the Airturn is in "iPad mode". This mode will send out arrow up and down keys to unrealBook Mobile.
(Here is the Airturn Manual)
Set BT Connected ON in the Settings window for unrealBook Mobile.
Display a file and then press the pedals to turn pages. Note if you have a 4 pedal Airturn, the 4th pedal will start and stop the music player.