Is there a way I can add a Digital Signature to Questionnaire? Use case: A Patient should sign the questionnaire before submitting it. I really appreciate any help you can provide.

Good question. FHIR does have a Signature data type, say you wanted to build a "signed document questionnaire response" - you might consider creating a DocumentReference that captures the contents of the questionnaire and add the signature to the context. You could also consider creating a PDF representation and attaching it to DocumentReference. A bot could be the way to do it. https://www.medplum.com/docs/api/fhir/resources/documentreference https://www.medplum.com/docs/api/fhir/datatypes/signature

For signing arbitrary FHIR resources, the Provenance resource type can also be used to hold a digital signature. This can also be used to give context about who signed the resource, etc. https://hl7.org/fhir/provenance-definitions.html#Provenance.signature