1. Open radykal-fancy-gallery.php and go to line 34 line that starts with these lines:
public static $add_script = false; //loads the core js files public static $add_pp_script = false; //loads prettyphoto js files public static $add_fb_script = false; //loads fancybox js files public static $add_inline_script = false; //loads inline js files
2. Set the first to true and also the variable(s) to true that are handling the loading of lightbox/inline gallery js files. So if you would like to use FancyBox, set $add_fb_script to true.