Add a PDF Merge Button to the Context Menu of Your Mac
Merging multiple PDFs on Mac is as easy as dragging and dropping them into Preview, but if you’re merging many, it’s still a tedious process. Jacob Salmela shares the Automator action that adds a PDF merge button to the context menu.
To add this menu, you’ll create a new Automator activity (Applications> Utilities), add some code, and complete it. From there, you can simply select two or more PDFs, right-click, then choose Services> Merge PDF to merge them all together. Check out Salmela’s website to find everything you need.
Combine PDFs right in OS X with a right click | Jacob Salmela