That being said, since version 0.5.0, you may have some success in decreasing the size of the PDF (and even censoring some parts) using the option to use Ghostscript to optimize the final PDF. krop only adjusts which parts of a PDF are displayed the original content is still there in the file and will, for instance, show up when editing the file in inkscape. Unfortunately, there is no simple way to eliminate unnecessary/invisible parts of a PDF file. Please report bugs or feature requests at where the source code for krop is hosted.(In fact, I initially wrote krop to be able to read mathematical papers on my Nook.) This is particularly useful, if your eReader does not support convenient scrolling. A unique feature of krop, at least to my knowledge, is its ability to automatically split pages into subpages to fit the limited screensize of devices such as eReaders.
How about a brief guided tour & screenshots?