Responses to Jerry and Rick:
I do my routine laptop work with the display set to 125% scaling, so I need to reset to 100% scaling before Publishing the PDF files. I consider this a bug within RM, because I have no such print size issues printing from browsers, spreadsheets, word processor, etc.
All of my scrapbooks are generated with 1 image per page, so that any media at max size of 3000 pix wide x 5000 pix high is nicely readable. Larger media get Photoshop processing to reduce to max height or width of 5000 pix.
I use RM's
Caption field to describe the media (census info, identity of person documented, etc.)
Description field records where the image came from (Ancestry database name, Find A Grave contributor, photos by me, etc.)
In my scrapbooks, many of the Scrapbook List facts have only one image, others have two or more.
EVERY image that documents the research gets included in the scrapbook. It's true that RM doesn't conveniently re-arrange image order for a fact, so I plan carefully what order to link the media files. On the other hand, re-arranging the Scrapbook List facts is as simple as revising the Sort Date, so that's really a non-issue.
Census images go through processing for:
1 - crop off excess non-image margins
2 - resize to 3500 pixel width
3 - adjust levels to improve readability
4 - add a red box to focus on the lines of interest on the census page
Newspaper images get similar processing:
1 - crop off excess margin material
2 - resize to 5000 pixel height
3 - adjust levels
4 - Save under my original filename, such as "18840410_IL_marriage_Chicago_Tribune_Thu__Apr_10__1884_pg8col5.jpg"
5 - crop the page to show just the article and page info (newspaper title, date, page #)
6 - SaveAs under a revised filename "18840410_IL_marriage_Chicago_Tribune_Thu__Apr_10__1884_pg8col5_crop.jpg"
7 - on full-page newspaper page, add a red box around the article of interest
Images of indices of BMD lists also get similar processing.
For the newspaper images, both full-page and cropped views get linked to Scrapbook List fact, source citation, and at least one individual fact. This gives my readers the context of the full-page image, and the readability of the cropped image.
Small images (obit photos, headstones, draft registration, BMD certificate, etc.) are resized, usually larger, in Photoshop to 1500 to 2500 pixel width
I point out to my readers that when looking at the PDF scrapbook files, they can resize (enlarge) if they want to see more detail of images like census pages. I think it is pretty rare for my readers to do so.