If you are having that much trouble filling that section out, you likely wont be in United or Delta's wheelhouse anytime soon. I'm sorry it that sounds harsh, but it might be telling that you are a rank and file that has no other experience besides flying an RJ. If that's the case then you will be looking at a significant up hill battle to get recognized.

By getting envolved with company related committies and union volunteerism, you'd be surprised how easy that box is to fill out. I'm not saying it's a deal breaker if you don't have any extra work experience, but 95% of guys I know at United easily filled this box with their outside the flight deck experience.