Roman Numeral Analysis
MuseScore supports Roman Numeral Analysis using the command Add > Text > Roman Numeral Analysis. It works exactly the same way as chord symbols - select a note, start the command, type your symbol, press Space to move to the next note, etc. But unlike with chord symbols, you will also see the special formatting while you type. So, if you type I64, you will see the 6 superscripted, the 4 subscripted. This is because this feature uses a special font I developed. You don't need to do anything special to install this font, but see below if you'd like to use this same font in other programs.
The font I created for use in producing Roman numeral analysis actually works in pretty much any program that can use fonts. I have tested it with MuseScore and LibreOffice, and I assume it will work in any commercial alternatives to these free and open source applications.
Here are links to download it in Open Type (OTF) and TrueType (TTF) formats:
Choose whichever you like, they should be both work.
To use the font, just install it normally (e.g., on Windows, double-click the download file then click the "Install" button in the dialog that appears), then select and use it normally in your program of choice.
Feel free to leave comments with any suggestions or problems you encounter using Campania!