You can find the RTP percentage for most of the games in the 'How to Play' section. Simply click the game you wish to play, select 'More Info' and then 'How to Play'.
The location of this section does differ from game to game, however it can usually be found in the game menus, or through a ‘?’ symbol.

All individual game RTP’s are shown within ‘Game Information’. Most Casino games display an informative pay table and the Live Casino games contain bonus round and multiplier RTP’s.