Bind a signature field to a PDF widget — same captured image flows in.
Add a signature line to an AcroForm template
When you'd use this — your AcroForm PDF has a Signature widget you've
never wired up. The visitor sees no signature pad on the form yet, and
the rendered PDF comes back with an empty signature box. One form-side
field plus one mapping entry connects them.
1. Add the signature field
Open the form in the admin shell and drag a signature field onto
the page where the consent lives. Set the key to signature and
mark it required. The published schema now carries
{ "key": "signature", "type": "signature", "required": true }, which
is the payload key the AcroForm renderer will reach for at render
time.
2. Bind the widget in the field mapper
Open the form's PDF templates panel and click into the AcroForm
template row. The widget inventory lists the Signature widget — a
real PDF signature field, not a text widget, so the mapper's validator
only accepts a signature-shaped binding.
Pick System token in the dropdown for the Signature row and
choose __submitter_signature. The saved entry looks like this:
{ "Signature": { "type": "system_token", "token": "__submitter_signature" } }
The validator pairs the token with the widget's declared type on save
— if the widget weren't a signature widget the row would come back
with a type_mismatch error.
3. Save and re-publish
Save the template and click Publish on the form. The next
submission's pdf_download_url returns a consent.pdf with the
visitor's drawn signature composited into the widget as a native PDF
signature field, not a flattened bitmap.