I don't own this computer, but I can confirm that you can effectively mark up a PDF document using any Windows 10 PC that supports a digital pen. This would include, of course, the latest HP Spectre x360 15-inch (and 13-inch) models. On my Surface Pro 3, I use the Drawboard PDF viewing app ($6) for this function. But you can also use lots of other apps for inking (fancy word for using a PC and digital pen as if they were a "real" pad of paper and pen), including the EDGE browser built into Windows 10. This capability is one of the most important reasons I would buy a 2-in-1 PC today instead of a traditional laptop.