This can be achieved by storing a reference to the signature image in a field on the User record and using that field in the merge template. This approach allows each user to maintain a single signature image that can be reused across all merge documents, without attaching the image to every individual record.
The recommended approach is to upload the signature image to the Salesforce Documents object, copy the Document ID, and store that ID in a custom field on the User record (or on a related object). In the Word template, reference the field using the Apsona image syntax:
«Signature@IMAGE,W=150»
During the merge, Apsona reads the stored Document ID, retrieves the corresponding image, and inserts it into the document.
Alternative approaches include storing the signature on a related Contact record using Apsona’s attachment surrogate method, or storing an externally hosted image URL and referencing it with the @IMAGE tag. However, the Documents object approach is the most reliable because Salesforce User records may not allow direct file uploads in Lightning, often showing “No actions available” in the Files related list.
For reusable assets such as signatures, it is best to store the image once and reference it dynamically through a field, rather than attaching duplicate copies to each record.