Paperform supports e-signatures. When one is captured, it's stored in your Paperform Results dashboard as a URL pointing to the image of the signature. Sometimes, when you open the image directly from the dashboard, it can look like a black page with nothing on it.
The reason the signature may appear empty is usually because the image is transparent, and some browsers will display transparent images with a dark background by default. You can resolve this by saving the image with the right-click menu in the middle of the page.