If you want to sign a document occasionally you can use a PDF certificate on a (USB) PKI token. To sign a document you'll also need signing software and a USB-port.
Trusted by default
Signing with this certificate guarantees the origin and content of a doucment. The certificate is included in Adobe's AATL program and is therefore automatically trusted in Adobe Reader. The signature complies with PAdES. Ensured e-Sign is an advanced electronic signature (AES) as described in Article 3 under 10 and Article 26 of the eIDAS Regulation. The department-specific Ensured e-Seal is comparable to an electronic signature but is used by legal persons and not by an individual person.
The longer the validity, the higher your discount.