sorry, but this not quite nice :-( have a look at the cursor placement, for example if putting between "die" and "neue"
RadRichTextEditor is using native GDI rendering, this is intentional because the native functions enhance the overall performance of the control. GDI+ text rendering can be accomplished by creating a custom RadRichTextEditor control and a custom RadRichTextBox. The attached project (RadRichTextEditor_GDIPlusTextRenderingExample.zip) demonstrates how can be achieve it.