I’m w/o an iPad temporarily and needed to sign a PDF that didn’t have a signature form. I clicked the little Apple Pencil icon and there was a little signature looking button, which instructed me to sign a white piece of paper and hold it up to my webcam. I did and it make the perfect little signature to be placed on the file. Also, it seems I can reuse it in other files, too.
I love the feature, too. I set up a Keyboard Maestro macro to make that lower toolbar appear automatically, since I always use it. I also set up a variation on David’s double “Command-P” trick (used to save as PDF), but mine saves to Yoink. So my secretary sends me an email with something attached that I need to sign. I double click the PDF, attack my signature, and then Command-P, Command-Y, and the signed PDF is on my floating Yoink window, for me to drop into a reply. As I type this, I’m thinking I could probably automate this further to automatically create the reply and attach the signed version.