Footer image not resizing in printed documentation

RH11

Does anyone know why an image inserted into a footer master page is not automatically resizing to the width of the printed page when applied to a print layout and output to Word? If you insert an image into the body of a topic or a master page and generate printed documentation, the image automatically resizes.

I'm trying to insert a high-res footer image (300 dpi) into my footer so that it appears on every page, but at the moment it's being embedded at full-size.

Thanks

Jonathan