Hi,
You won't be able to create watermark below the main contents with the HTML to PDF converter this way. This is because most of the time a white solid background will be rendered for the main HTML output. This white background will completely block whatever you have rendered into the page in BeforeRenderPage event.
There are two alternatives:
1. Rely on the afterConvertHandler argument of the RenderAsPDF method:
https://www.essentialobjects.com/doc/eo.pdf.mvc.mvctopdf.renderaspdf_overload_2.aspxHowever this will render additional output above (not below) the main contents. This is the closest to a watermark.
2. If you must have watermark below the main contents, then you can consider modifying your CSS to apply additional style to your body element through this property:
https://www.essentialobjects.com/doc/eo.pdf.htmltopdfoptions.userstylesheet.aspxThe disadvantage of this option is that it's hard to precisely control the position of the watermark since the CSS layout depends on the document layout. For example, if your HTML is only half a page, then it's impossible to create a full page watermark.
Hope this helps. Please feel free to let us know if you still have any questions.
Thanks!