I understand that they can be exported as a CMYK pdf - but I'm splitting a project with another designer and she needs to get me all of her files - many of which are RGB - need them CMYK. Thanks!
You can't convert the color mode of links during packaging -- and you don't need to, most likely. Why do you think you must have CMYK? Unless you know the correct output space now, and have no plans to re-purpose the file in the future (and even if those things are true and you don't need to make post conversion adjustments to the color) there is no advantage, and plenty of disadvantage, to converting to CMYK before export.