If you know the correct program (.exe) to associate with the .rdf file, then find an .rdf file, RIGHT click on it, choose "Open With", then select "Choose Program" from the little menu. At the next "Open With" dialogue window, place a CHECK mark in the "Always use the selected program to open this kind of file", then find the correct program and double click on it.
Hope this helps.
How do I unassociate a file type from a program? Somehow an accounting program got associated with type RDF. I need to unlink them.