Step 3: Add PDF, JPG, PNG and other additional files to Preview by dragging and dropping them into thumbnails sidebar. If your file isn’t opening in Preview at default, you can two-finger click on that file then go to Open with > Preview. If it isn’t, go to View > Thumbnails or press Option+Cmd+2. Make sure that the thumbnail sidebar is visible.
Step 2: Double-click on the duplicate file to open it in Preview. To create a duplicate, simply two-finger click on the file and select Duplicate in the dropdown menu. You want to use a duplicate to make the changes in, so that you’re preserving the original file, in case you make a mistake or need it for something else in the future.
