Sorry for the delay in response and thanks for sharing the help article used to follow the steps.
There might be some step skipped to assign the stamp field. Did you also refer to the steps suggested in the help article where its explained in detail, how you can add stamp to the document and assign it to the signer? You may go through the tutorial here: Sign with a stamp |
Hope this helps. And if you have managed to find the solution to this problem, then please help us with your finding.