Do your feet hurt even when riding? Usually one does not do a ton of walking in their riding boots. If you have PF then I would suggest you do the walking required in the shoes that are best for you foot , then when hyouare are ready to ride , change into the riding boots. I have had PF for years. It was really bad for two years. Walking was a real drag. I had orthotics made from three different sources. I had injections dirrectily into the heel (yow! That hurts!) I ate antiinflammatory drugs like candy, iced the foot after walking, did this and that stretch . And on and on.
Finally, I got a good doc who made me good orthotics, and I wore "Haflinger" brand slippers around the house, ditched my Birkenstocks, never walked barefoot and little by little , it got better.
I wear good running shoes that are the most torsionally stable (Brooks). I wear my Haflinger slippers around the house (love them!!!!!) , and wear Dansko clogs when out shopping or other activities with a lot of standing. I never wear fashionable shoes that have no support. I walk barefoot only for short periods of time, and I carefully engage the muscles of the bottom of my foot to forcefully create the arch that I lack.
If I wear dress shoes for a few hours, I am ok, but if I feel the slightest pain, I back off to the orthotics. It's management, not a cure.
Shoes with a stiff bottom , such as hiking boots, are best. YOiu'd think soft is good, but NOT SO. A boot with a "rocker" to the sole or a steel shank is best.
The Cobalt series of boots by Ariat are better, and then take out their insole and put in either your orthotic, or a "Super Feet" store bought orthotic, so you can keep your real custom made ones for your daily use shoes.
CUSTOM MADE is the key. It will cost 3 to 4 hundred dollars, but worth every cent.