While not really related to specifying multiple sizes, PDFs do have the concept of an artbox, which could be used by the PDF author to indicate the area of the page that actually contains content.
A useful feature of a PDF reader on these devices could be to display only this area with a smaller, perhaps user defined, margin.
This at least would fix the 'huge margin' problem.
A useful feature of a PDF reader on these devices could be to display only this area with a smaller, perhaps user defined, margin.
This at least would fix the 'huge margin' problem.