Secure Document but Allow Signatures Only

[Dustin Slaven]

Hello, 

I can see my options when creating a new security profile, that I can allow printing and form fill and signature's to a password protected document. How can I set it up so ONLY signature's are allowed and the rest of the data I enter into the fillable forms remain locked down. Or can you show me what steps I need to take in order to generate the appropriate PDF document. I could be missing steps on my side.

Example -

PDF document for an invoice, it has lines with the item and the cost, and the total amount owed by the recipient. They need to be able to sign the document only and return it back to me without being able to edit the rest of the document.