Dont use this Addon!

1. It adds annoying watermarks to PDFs

2. It requires a server to process the PDFs, i.e. tracking, this is bad for your privacy!

3. It seems to add Spam links to search engine results (I got a P*rn link added as the first result of a SearX engine not displaying ads...)

Use this addon instead, it works perfectly and offline!

https://addons.mozilla.org/de/firefox/addon/print-to-pdf-document/