You have to embed the font within the project.
The best way to go about this is to create a seperate swf that only contains the font within it's library. You also need to select 'Export in first frame' and 'Allow runtime sharing' while including the font into a library.
Doing it that way means that multiple swf's can reference the font from a single source, saving approx. 15-30Kb of bandwidth each time.