Retro-Schulzi WHDLoad
To use WHDLoad games you'll need to have a prepared WHDLoad image named 'WHDLoad.hdf' in RetroArch system directory.
In this WHDLoad image you must have the three kickstart roms (kick34005.A500, kick40063.A600, kick40068.A1200) in 'Dev/Kickstart' directory.
To do this, you can consult the excellent tutorial made by Allan Lindqvist (http://lindqvist.synology.me/wordpress/?page_id=182) just jump to the 'Create WHDLoad.hdf' section.
The core only support HDD image files format (hdf and hdz) and slave file must be named 'game.Slave'.
https://github.com/libretro/libretro-uae