If you have Adobe Acrobat one idea is Add a Watermark from an image file, keeping its opacity as 100% and setting the image position as needed, such as at the top-right of each page.
To do this go to menu View -> Tools -> Page, click on Watermark and choose Add Watermark.
Then you will be able to choose an image file and configure its position.

Another idea is to place a button using an image as an icon in its layout and duplicate it across pages, flattening the pages with a script after that.