Click Merge files. Click on the Annotations button (pencil icon) then the Signatures button then choose yourAdobe Acrobat Reader is a versatile PDF viewer, great for Mac users. Then sign your signature on a piece of paper and hold the paper up to your Mac’s camera. When your signature looks correct, click Accept. The Merge tool makes it simple to combine PDF files whether you’re working on a Mac, a PC, or a mobile device like an iPhone or iPad. How to sign a PDF. Launch the PDF file you want to