Rice & Powell may not have been required to sign the form. The policy might have been put in place subsequent to their tenures.
Petreus had to sign the form. It was used to charge him with a crime. If the head of CIA had to sign, I’m sure the head of State had to sign.
I’m sure Condoleesa Rice and Colin Powell had to sign too. We will see. If they can’t find their forms either, they need to ask Powell and Rice, who they gave the form to when they left.
I believe you are correct on the forms. Seems that this form was put in place after the others and before Hillary.