How to attach Referer in the PDF which is generated using mPDF library

As I am generating a PDF using mPDF library. My concern is that, the PDF contains the assets (like images), these images having the domain restriction (i.e. no one can access these assets directly, these assets are accessed only from the specified domain).
So when I add these assets in the PDF’s html body, these assets get blocked (i.e. they are not get displayed).

Can this problem be solved by attaching the referer to the PDF?