Illustrated below are additional gestures that are available during the time that you are using Splashtop Whiteboard.
The Whiteboard Toolbar displays at the top of the screen when Splashtop Whiteboard is launched, but you can hide it anytime using an upward two-finger swipe; and you can re-display it using a downward two-finger swipe. In addition, a two-finger swipe to the left will advance to the next page of the document you are using for your presentation (just like the "Page Down" arrow key on a keyboard). Conversely, a two-finger swipe to the right will go back to displaying the previous page/slide (like the "Page Up" arrow key on a keyboard). 
NOTE: Alternatively, you can also use the Previous Page and Next Page buttons on the Toolbar.