Using a Powerform from your app is essentially a one-way maneuver: once you redirect the user to the Powerform, you can't get him or her back, AFAIK.
What is your use case? Is the signer someone within your organization? Who is the sender of the signing request? (You should edit your question, not add the info vai a comment.)
If your use case is that someone comes to your web app, fills out a form, and then wants to sign it, then you can either:
- Redirect the person to the Powerform at the end of their interaction with your website. After they finish signing, they are "done." Your app can subscribe (via Connect) to learn the envelope ID that was used.
- Use a Powerform in an iFrame with a big button above the iFrame marked Return to the app -- This solution is highly not recommended since it is a poor user experience and won't work on a mobile device.
- Recommended: Create a custom envelope/signing request for the web app visitor by using Service Integration authentication with DocuSign. Then present an embedded signing ceremony to the web app visitor so they can sign. After the embedded signing ceremony, your web app will be redirected to by DocuSign so your app will regain control of the session. No iFrame is needed in this pattern either.