If you want to write some formatted output to an RTF file then you have 2 options:

• Learn about the RTF file format and write a method which transforms your original text into this format
• Use an existing module which already does that. Searching for "rtf" on CPAN returns many results, so going through these results would be a good first step

Maybe I also misunderstood your question, but to me it sounds like that's all you want