run
rpm -ivh --nosignature xdfr-2.0.1.src.rpm
but rpm exits with error message:
error: xdfr-2.0.1.src.rpm: rpmReadSignature failed: sigh load: BAD
error: xdfe-2.0.1.src.rpm cannot be installed
I think the problem sits with the person/group who
produced that source file.
and they will need to add a fix, probably resign it.