If not possible to bolt the heel rest on the unused holes:
• it should be held on the same bolts used to fit the pedals.
• it should be placed between the pedal base and the internal chassis floor in a way that the bottom
surface of the pedal bases are fully supported by the heel rest.
• It should be fixed with holes, oblong profiles (like keyhole or button hole) are not possible.
• the length of the bolts to install the pedals shall be increased accordingly to the heel rest thickness.
Please refer to the pictures below as reference example.