Then click Choose. Preview will direct you to open the images you want, so browse to the folder where they are kept and select them. Select PDFs to merge Missing: mac On your Mac, click the Finder icon in the Dock to open a Finder window. Drag and drop PDFs to merge them into one file with our PDF combiner. Note: The files appear in the PDF in the same order that you select them. Whether you use software that comes with your Mac, sites, or paid options, here's what you need to know about how to