Maybe you can use the RTF editor provided in sample programs, eg., blue bar to create the text you intended to display and save the file somewhere. There rename the file to abc.txt (on windows) and view it as ASCII text, and copy the text to your program.
Sorry I don't know much about Upp RTF format yet. Here is the output of my experiment:
[ $$0,0#00000000000000000000000000000000:Default]
[{_}
[s0; [5 uWord]&]
[s0; Using [*^www`:`/`/upp`.sf`.net^ Ultimate`+`+] technology.&]
[s0; Which excels!]