how to enlarge size picture ahead of pdf Macbook

I have the following issue:

I have a pdf file, a comic book. I would like to add on the top of the document a jpg (the volume cover). What I do is:

• Open pdf with Preview
• in the sidebar I select Thumbnails
• then I drag and drop the jpg file on the top of the pages

This works, but I have a white border around the picture (result in the attachment).

How could I avoid this? maybe resizing somehow? It results always with the border, for whatever pdf and cover page I try

Thank you

It's likely that the JPEG is not the same size as the page size of the PDF. Preview is 'placing the JPEG' on an empty page, which is why you're getting the white margin.

Your best option is open the JPEG in Preview and use "Export..." (NB: not "Export As PDF". This will create a PDF without margins, and you can drag this into place.

The other option is use a DTP package to correctly size the image on the page format you want, without margins.