An open hole packer uses mandrel expansion and a surrounding sealing element that can optionally have a swelling feature and further a seal enhancing feature of a ring with an internal taper to match an undercut on the mandrel exterior. As a swage progresses to the taper at the transition between the ring and the extending flat fingers, the fingers get plastically deformed in an outward radial direction to push out the sealing element. Shrinkage of the mandrel axially due to radial expansion brings a ring on the mandrel outer surface under the fingers to act as a support for the fingers against the seal which is pushed against the open hole. Mirror image orientations are envisioned to aid in retaining pressure differentials in opposed directions. Another external mandrel ring extends into the seal to keep its position during differential pressure loading.