On Mac you can drag a PDF file from the Finder to the Documents app window. You can also drag an article from the Desktop into the open Documents window. · You can combine any number of PDF files. You can use the 'Add Files and Folders to Document' or the 'Create Files on the fly' feature to choose where you want to merge the documents. How to Combine Multiple PDFs into one PDF file in PowerPoint? If you have a lot of PDFs, you can combine multiple PDFs into a single .ppt file. Click to create a new PowerPoint presentation. Click the 'Files' button and then choose 'Add to Presentation'. To add each file at a time click the 'File' button and click 'Add to Presentation'.