Adding text and setting color in a RichTextBox, will only work if your dealing with small amounts of data, less than 2MB. I'm building a compare tool and my ASCII compare uses this method and the Binary compare builds the RTF in the correct format, however, the spaces are killing me after a color is set and when it's "\f0" turned off. AI states that this will resolve it, "\~", but it doesn't. Looking for the middle ground solution.

This is my compare tool I'm still working on, but the ASCII uses what I'll be changing soon, while the binary uses the RtfBuilder class and works pretty good, outside of the extra spaces I have to deal with. Maybe future people can use some of this code to help answer how colors and fonts in a string then loaded afterwards into a RichTextBox. It's not an extensive RTF class, only the basics.
https://github.com/gavin1970/Chizl.FileCompare/tree/master/rtf

I could always use help working on it, if anyone would like to join. Ping me here or through github.