If you create this watermark app but then move the file you’re using to watermark PDFs, it’ll break everything. This could be pretty much anything you want, but not only do you have to know where it lives in your file system, you’ll have to leave it there for my steps below to work. The very first thing you’ll need to do is locate the image (such as a file in JPEG, TIFF, or PNG format) you’d like to use as a watermark.