You could use the SignaturePad widget to sign a PDF. So, for example, if you have a digital form where the users enter their name/address for the PDF, just add the SignaturePad widget to the page. The SignaturePad is an HTML canvas where users can draw on, meaning that they can therefore provide their digital signature. This knowledge base article describes how to use the SignaturePad in further detail: https://community.simplifier.io/knowledge/drawing-on-images-with-the-signaturepad-widget/
In the SignaturePad’s property ‘image’, the base64-encoded image data is stored. You can use this base64 data in a PDF template, as the parameter ‘src’ of an HTML <img> tag.
With this approach, the digital signature is included in the generated PDF.