I can't get hold of chicken feet for bone broth, is there something else I can substitute with?

You can also use wings and backs (harder to find). You can also order chicken feet from US Wellness Meats or you can leave them out. 

You may also want to search for a Weston A. Price Foundation in your area to ask for other recommendations.

If you do eave them out, you can add collagen to your broth instead.