Is it best to use RGB color-space when you don't know if the end-user of the document is going to be printing the document on an inkjet or laser printer? For example, even though my home printer has 4 cartridges (CMYK) it still uses RGB 'drivers'.
I would not assume the person receiving your resume will print it, unless they've told you so.
Personally I would stick to RGB for a few reasons:
Your resume will likely be viewed on screen. I don't know any studios who print out all the resumes they receive, it's too much. If they DO print your resume out, at this point I would think the interview will make the difference.
Second, you will benefit from a larger gamut which will make your work look better than CMYK.
You do not need to work in CMYK... Unless you need to.
The only reason somebody needs to work in CMYK is when your project needs to be printed on a commercial print, (offset print).
In some few cases, you can send the file in CMYK if, again the provider really needs it. Some inkjet plotters do use the data from a CMYK file.
But most of the time, home, office, small copy shops, laser printers, inkjet printers use the RGB values and re interpret them to whatever values they need. Sometimes it is CMYK, other times is CcMmYK, some other CcMmYKk when you have Light Cyan, Light magenta, light black.
But normally you need to simulate colors, so you do not end with fluorescent colors if you will not use special inks.
Sayed that I agree with Emilie.
They most likely will not print your work.
A CMYK file can potentially look bad on a visualizer that do not support CMYK profiles.
RGB files compress better than CMYK ones.