How to add Watermark in exported pdf file

I need to show watermark on each page of exported file, and the watermark needs to display the name of the exporter.
Please tell how to do, Thanks!

Hi @David.Xu,

How is your question different than the one, which you also checked and responded to?
Duplicating questions on the forum doesn’t guarantee a faster or a better answer.
Please follow the other topic and when someone with knowledge on the topic will answer, you will know.
Please keep in mind that the XWiki experts are answering to the forum questions in their free time.

Thanks,
Alex