Apple - Paste image from the clipboard into a PDF in Preview
You CAN do it. At least this is what worked for me on MacOS Catalina and Preview Version 11.
- Copy onto the Clipboard, the image that you want to paste on your PDF page.
- Go to Preview -> File -> New from Clipboard.
- This will basically create a new Preview document with your image in it. Now click anywhere on the image, press Cmd+A to select the entire image, press Cmd+C to copy and then (this is the crucial part!!) press Delete to delete the image.
- You will see a blank screen in Preview since you have deleted the image. Press Cmd+V and your image will reappear, but now, in a different format that can be copy-pasted across Preview documents.
- Finally, select this 'new format' image using Cmd+A, copy it using Cmd+C and navigate to your PDF document and paste using Cmd+V.
Voila! You can paste the image anywhere in your PDF document and on any page and you can resize and edit it just like you can with shapes. I think Apple didn't intend this to happen and I hope they don't read this and change this feature :P
Based on @Allan's comment that Preview does not support PDF's. Preview does support some basic image editing facilities: so I am making image copies of the pdf pages and then super-imposing the other images on top of those images. This is working for my present needs.