Users on a team plan (Studio, Company & Company Plus) have the option to add custom cover and back pages to storyboard PDFs. This is not available on Free plans.
Cover and back pages can be multiple page PDF documents if you wish, but they should be:
A4 in format (other sizes will be stretched to fit)
Basic PDF documents (optional content or interactive PDFs are not supported)
No more than 10MB in size
Repairing malformed PDFs:
If you see an error after generating a PDF indicating that you have a malformed PDF cover or back page, a possible solution is to re-export the cover/back page, then upload it again.
On Mac, you can do this with Preview by going to File > Export as PDF... in the menu.
On Windows, you will need a PDF reader (such as the free Adobe Acrobat). Once you've downloaded that, just save out a new copy of your cover/end page and replace the existing file.
How to add a custom cover/back page
First, open the storyboard that you want to export. Click Download, then select PDF from the dropdown menu to access the PDF exporter.
Select the Front cover tab on the left-hand side.
Then, check the "Use custom front cover" option.
When you check this box, you'll see options to upload a PDF cover page and a back page. To upload a back page, just click the "Back cover" tab on the left-hand side.
Both front covers and end pages are specific to each storyboard, so changing them for one storyboard won't change the covers for any of your other storyboards.
To learn how to change the display of cover & end pages, take a look at this article.