Read the miscellaneous information
Various bits of information that don't fit elsewhere. This page is well worth reading just in case any of the titbits apply to you or your situation. There's an index list that you can scan to make it quicker.
Margin sizing tool
Try the margin sizing tool
A simple margin sizing tool that may help you with the size of your chart's margins. Simply drag the gray part of the tool around (which represents the main part of your chart) and the sizes are updated for you automatically.
Look through the API documentation
If you want to delve into the code of the RGraph libraries then the
documentation is a good place to start. It's quite extensive (there's
a lot there) so you may find that simply delving into it and getting the
information that you want may be a good way of getting through this page.