a) Kneel on the floor. Bring knees and feet together and sit on your heels. If this is uncomfortable, you can put a pillow under your bottom.
b) If this is comfortable, sit as in 'a' then spread the feet apart and sit on the ground between the feet for more of a stretch. Do not let the feet turn out.
c) Sit as in 'a' and then put the hands behind you and rock back so that the knees come off the ground. This opens the ankles.
d) Kneel down with knees and feet together as before then curl the toes under and slowly lean back until eventually you sit on the heels or until you feel the stretch.
Poses that help PF would be combinations of downward looking dog (stretches calves and bottom of feet) and upward looking dog (stretches tops of the ankles). Half lotus or full lotus would be beneficial for the outside of the ankles. Any inverted pose (shoulderstand) should improve circulation to the feet. To improve circulation and promote healing, massage ankles, tops and bottoms of feet, and the achilles tendon. Massages of the plantar fascia would include rubbing along the length of the fascia and across the fascia. Someone said visualize this as ice crystals that need to be broken up. After a massage of this type, a foot bath with epsom salts helps me relieve any residual pain.
Be patient, after 3 months of doing this daily in combination with the recommended stretches and orthotics, I have seen a 90% improvement in my feet.