1) Open your RR installation directory and search for the "LAUNCH" directory.
2) Open the "LAUNCH" directory and create in it a new directory named "File manager".
3) Open the new directory and create in it a new text file named "File manager.ini" and write in it this code:
PATH = [app path]\filemanager.exe
TryEmbeddedTimeOut = 5
where [app path] is the path to filemanager.exe
4) Optionally you can add a picture as icon in the directory.