How you can sign a PDF using a digital signature?

First of all, make sure the PDF you’re planning on signing is eligible for electronic or digital signatures. Digital signatures are necessary only for files that require complete authentication with encrypted certificates. You'll need to order specific keys via authorized institutions. However, you can get your sample verified with an eSignature as well. Consider utilizing a service like airSlate SignNow. It allows you to eSign documents without any additional software on your desktop or with a convenient mobile application. Upload a PDF, add your signature, and save the file.