This format is actually a Standard Midi File with a RIFF-Header in the beginning. Since this is a RIFF-subtype, the file can contain some additional information ("Artist", "Creation Date", ...)
RIFF Midi Files can be played back with the Windows Media Player.
Quick Info:
Name: Windows RIFF Midi File
Type: Music
Extension: RMI
Viewer Application: Windows Media Player
Specification: See RIFF Format
If you have additional information, send mail to
Alexander Krauss