Not clear how to use preview to make a pdf with multiple images. I'm guessing that is something that is easy if you have to do it often? I'd probably reach for html or word. Probably word, first.
The easiest way is to open your PDF document in Preview, turn on View > Thumbnails (if it isn't on already) and drag and drop your image document into the thumbnail pane.
You can combine entire PDF documents this way, either dragging them from a Finder window or dragging the title bar icon from an open document.
You can also drag and drop thumbnails between open PDF documents in Preview, and you can create a new document from the clipboard if needed using File > New from Clipboard. (Note if you want to drag other pages into it you will need to save it as a PDF first.)
Not clear how to use preview to make a pdf with multiple images. I'm guessing that is something that is easy if you have to do it often? I'd probably reach for html or word. Probably word, first.