I have an example data file in .rtf format but Omniscope does not read this properly. The main separator looks like an underscore "_" but I when I load it into Omniscope it comes up with an unrecognised character:
The character in the rtf file that you have as a main separator is ascii character 01 (normally called SOH) , this is normally a control character. If you use a text editor such as Notepad++ you can see it displayed as SOH and can copy the character and paste it into the separator field. It cannot be displayed as a character because it is a control character.
We do not recommend importing your data from a rich text document as text.
That was just the format the data was provided by our data supplier. I think it will be fine for now to copy and paste the SOH to read the data. It's only a temporary thing which will could change later on.