I always put down my legal name, and then introduce myself as Evan and if they ask explain that I'm trans. I've had responses vary from those who just didn't even think to question that I'm male (even though my ID clearly says female), to those that I have to explain it to them and they smirk through the whole interview. I don't think you can put anything other than your legal name on an application.. the best advice I can give is just be confident, be ready to educate them, and don't take anyone's stupidity personally. T or no T, if your ID still says female and/or your birth name, you'll be outed anyways.