Please open PDF Combiner for Mac OS in Mac OS, then click Add on GUI interface, and select dozens of PDF files in pop widow, then please click Open there, and you can notice paths of added PDF files could appear in processing form of GUI interface automatically. Here, on condition of saving precious time, you can drag and drop those PDF files into processing form directly, which can help you add them for process, too. And to remove added PDF files, please click Clear.

If you need to change page order in merged single PDF file during combine PDF, please click relative path of added PDF files in processing form, then select Up or Down below processing form of GUI interface according to your requirements; to edit converting page ranges of each added PDF file, please click edit boxes in column of Specified Page(s), then type page numbers or page range with "-" referring to examples shown to you there; to preview added PDF files by the way of each page on GUI interface of PDF Combiner for Mac OS, please click relative path in processing form, then type page number in edit box Page below Preview so that preview of each PDF could be shown there accordingly.

To select destination folder with GUI interface of PDF Combiner for Mac OS, there are 2 ways for you to choose:
Type path of objective folder in edit box Output Folder;
Or please click , and select a folder in dialog box, then click choose there.

When prepared work is done well like above, to combine PDF files with GUI interface of PDF Combiner for Mac OS, please click Merge on GUI interface. After a while, your single merged PDF file could be produced into targeting folder automatically.