Annotate webpages in Safari using Markup to highlight text, add notes, and share edits seamlessly on your iPhone, iPad, or Mac with built-in tools.

Use the Markup tool (the pencil tip icon) to add text, annotate, highlight, or sign the document. Tap the Share icon to send the document as a PDF via email or text.

Sign a document, annotate an image, or sketch a picture on your iPhone or iPad and then use it on your Mac with Continuity Markup and Continuity Sketch.

Opening the PDF in a new tab does, however, offer a band-aid solution. You can't use the native PDF reader to digitally sign documents, but you can use markup tools.