Where to get certificates for Acrobat PDF

This is mostly a link only answer, however I do know that if the signing CA isn't marked as trusted by the app (Acrobat in this case) then it won't be marked as trusted. That being said, this link talks about exactly what your asking: http://helpx.adobe.com/acrobat/kb/approved-trust-list2.html

I have found 4 organizations, trusted by Adobe Acrobat so that the signatures will be considered "valid" in Acrobat Reader, Standard, or Pro, that sell these certificates. They are all expensive (typically $300/year).

Note that Adobe has built things so that the person who signs a PDF document MUST use "two-factor authentication" at the time they sign the document. This means that simply purchasing and possessing the certificate itself is not enough. You must also typically have a USB thumb device on hand that you must physically stick into the computer while you sign the document, along with the certificate. (This explains the cost.)

Here are 4 organizations from whom you can purchase an Adobe-certified Digital ID certificate, along with a proper physical USB thumb device, that will be considered "valid" by anyone viewing your signed document in Adobe Reader or Adobe Acrobat:

• https://www.globalsign.com/en/pdf-signing/pricing
• http://www.entrust.net/adobe-cds-certificates.htm
• https://www.digicert.com/document-signing/
• http://pdfmachine.com/pdfmachine/prices_pdfmachine_sig.htm (pdfMachine sig pro, or equivalent, required)

What a pain! Thanks for making life so difficult, Adobe, by making this so expensive.