Creating an action button for opening the printer friendly version of a sheet

Just create an URL action button with the record URL adding .xhtml to the end.

For example, the sheet URL is https://www.ragic.com/demo/sales/1

For a record, the URL would be like: https://www.ragic.com/demo/sales/1/18

So for the action button, you can put down the URL:

https://www.ragic.com/demo/sales/1/{id}.xhtml