If you want to handwrite or draw something into a PDF document just follow the steps below.
- Open the Tool-Bar as indicated in the screenshot below.
- Tap on the Pen button.
- Now you can annotate or draw in the document.
PDF Pro comes with full features support for Apple Pencil®. If you are using an Apple Pencil® PDF Pro will recognize this automatically. If you are using an Apple Pencil® 2 you can switch between the Pen and Eraser Tool simply by double tapping on your Apple Pencil®.