Sign in to your PDF tool (Adobe Acrobat, Preview on macOS, or a trusted online e-sign service)
Open the PDF you want to sign
Choose the option for digital signing (e.g., “Fill & Sign” / “Digitally Sign” / “Sign”)
Select your digital certificate
If prompted, create or upload your certificate (from a certificate file or smart card)
Place the signature field on the document where you want it
Confirm signature appearance settings (name, reason, location, date)
Review the document for any changes or alerts about signing
Click “Sign” or “Apply”
Save the signed PDF (use a new filename)
Verify the signature status shows as valid/trusted in the PDF viewer
If needed, export the signed copy or send it to recipients for verification