Ragray was just a tool to patch kro client easier without many work and to evade the annoying "Can't patch" and "


" errors.
Rsu is the actualized version of it since, +/- at near November, Gravity changed the way how people connect to the game and Ragray wasn't enough to patch the new files.
To use Rsu you should use both 2 exe - rsu-kro-renewal-lite.exe and rsu-kro-rag-lite.exe or something near that[one at a time ofc].