@rebeccajg You don’t have to use iframes with iHomefinder IDX you can use the custom branding method inside iHomefinder. I’m sure of this as I’ve done an integration of IDX using iHomefinder on chucksellsdifferently.com Check the MLS Tools and Property search. No iframes.
Contact iHomefinder and/or work through the help docs. It’s not easy to wrap your head around to begin with but it is doable and actually not difficult but a little tedious.
Good luck.