After a signature is signed, it needs to be committed to the
Normally, this is done when you save the document. It happens
invisibly without you needing to do anything. However, sometimes,
you may wish to commit before the document is saved. This most
commonly occurs if you are working with documents containing more
than one signature field.
The PDF architecture requires that a document be incrementally
updated each time a signature is signed. It requires this so that a
PDF viewer can show what changes were made to the document between
the times it was signed. For this reason, if you are signing
multiple fields, each signature (bar the last) needs to be signed
and then committed in turn. The last signature does not need to be
committed because this is implicitly done by the final save.
After each commit, all previous references to form fields would
be invalidated. You need to obtain updated references to form
fields from the Doc.Form.Fields