Author here. I chose tkinter because it's included in Python, or so I thought. I wanted to minimize the complexity of installation.
The README lists alternatives and why I find them insufficient. Okular allows free-hand annotations, but not saving those for later use. It allows inserting custom saved stamps, but these will not be visible in other PDF readers.
As i had mentioned in github issues , it is outdated/misinformation . Please update. I had been using Okular to sign contracts for a few years and it works perfectly fine across all PDF readers.
The README lists alternatives and why I find them insufficient. Okular allows free-hand annotations, but not saving those for later use. It allows inserting custom saved stamps, but these will not be visible in other PDF readers.