First what codec have you selected? Also it would be helpful to post a screen shot of the output module you have selected on the computer that is not giving your a RGBA choice.
Johnny Cuevas, Editor
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.