Hi Dick,
Thank you for your interest in Essential PDF.
Thanks for the code snippet. I was able to reproduce the issue. Could you please use the following statement for adding a new page to the appended document?
C#
// Adds a new page to the appended document.
pdfdoc.Pages.Add(pdfdoc.CreatePage());
Here is a sample for your reference:
inserting_page.zip
Please take a look into it and let me know if you it meets your need.
Regards,
Dhivya.