Digital Signatures
A digital signature is a cryptographic signature which must be of type .pfx or p12
If you add an image, it should be displayed.
Please be sure to set "CopyToOutputDirectory=always" for the image file so that it can be located.
The image should appear in the Acrobat Reader Digital signatures bar.
https://helpx.adobe.com/acrobat/using/validating-digital-signatures.html