We don't have RRD here, so I can't give you any advice based on personal experience, but I think the pathogen is airborne, so planting other roses in purchased soil wouldn't eliminate the problem. Also, I think I've heard that burning the infected roses is likely to spread the pathogen, so you should dispose of them in some other way rather than burning them.
Andi's right about the wild roses. Rosa multiflora appears to be the culprit.
Sadly, all of your roses probably are infected by now, so all you can do is dispose of the obviously infected ones and enjoy the others as long as you can.
