When RTF reports are created on Linux, diagrams are sometimes not scaled properly. This is primarily due to the fact that there are no exactly equivalent diagram label fonts on Linux and on Windows.
The default diagram label font on Linux is
-urw-nimbus sans l-medium-r-normal-0-%d-0-0-0-p-0-iso8859-1
(as set in ToolInfo.LINUX86, variable font_name). Since this font does not exist on Windows, it is translated to Arial when diagrams are exported to RTF (i.e. in a report). Diagrams are not rescaled during printing however (since this would potentially mean changing the entire layout of the diagram to avoid symbol overlaps) so instead, the label fonts are scaled with a factor which is set in templates/ct/print_default.rules.
If the scaling of symbols in your RTF report is not right, look for the DiagramFontScaleTuneFactor rules in this file (there are 3, for different targets and papersizes) and decrease or increase the factor.
0.880 or 0.800 have been found to yield reasonable results (but this can depend on how the nimbus font gets scaled on your particular OS and screen resolution).