I had the opposite problem - I could not keep the 2 well cats out of the CRF food. So they all ate it, mixed with regular food. Now 2 out of the 3 need the CRF, so it all worked out - no dietary changes.
On another note, that brings to mind that not only might you need to have your pets medicine in a pet kit, but also provisions for refrigerating some of that medicine. Last week I started giving twice daily insulin shots to one of the cats. That insulin needs to be refrigerated or it dies. And since it has a relatively short shelf life, you can't just get some and keep it on hand for an extended "just in case" scenario.