Can I Add A Featured Artist to My Track?

Absolutely! Just make sure it is listed like this:
 
  • Example with 1 featured artist: Under Pressure (feat. David Bowie)
  • Example with 2 featured artists: Shortie Like Mine (feat. Chris Brown & Johnta Austin)
  • Example with 3 featured artists: Sweetest Girl (feat. Akon, Lil Wayne & Niia)
Also, adding a featured artist does not require any additional artist slots. Woo!