Here’s how it works:
Step 1: Double-click on a jpg from the Finder window to open it in Preview.
Step 2: Click on “View” at the top of the screen and select “Thumbnails.”
Step 3: Go back to your Finder window and move it so you can see the image list and the Preview thumbnails.
Step 4: Drag additional jpgs over to the thumbnail viewer.
Step 5: Make sure “Preview” is the active window.
Step 6: Select “File” and choose “Print.” (If you select the “Export as PDF” option, it will only save one page.)
Step 7: (Optional) Choose the orientation and uncheck Auto Rotate.
Step 8: From the bottom left corner of the window, choose “Save as PDF.”