In the RingCentral app, there's no option to customize the cover page yet. It's best to add it first in your Personal contacts so that when you enable Cover Page, it will automatically fill out information such as Name, To, and From. Then you can type other details in "Cover page notes.

With RC desktop phone app you can customize cover page

https://support.ringcentral.com/article/Fax-Create-a-Custom-Fax-Cover-Page-RingCentral-Phone.html

You can put cover page name, details, description, name, address, company name, contact etc

For those with the new RC desktop app with no fax cover page editor...

I would create a MS Word or other text file with the cover page you desire, add this to the file you would like to fax or attach it as one of the files to be faxed (attach the cover page file first!) and then use RC to send the fax with NONE as the choice for cover page. This is what I do....

Thanks for sharing this, @Richard Williams