Another user kindly provided stamps they were using that includes numbers with circles around them. I've attached these images with my post. If you download those files on your device, open the annotation editor, tap the stamp tool icon at the top, tap it again to view the window, switch to the User category, then tap + and "Local File", and select all the images, you can then place them on your scores. In general, it's better to use .svg files when possible as they scale to any size without a loss in quality. If you find these stamps aren't high enough quality for your needs, you will need to pursue creating stamps using a free tool like Inkscape. I've created stamps with it and once you get the hang of it, it's not too complicated.
