I could use my right hand in some circumstances, but I'm usually braking at the same time. If I'm going to be braking with only one hand, I prefer it to be the back brake and not the front. However, if I'm not needing to slow down drastically, I could very well use my left hand/front brake.

And depending on the circumstance, I may not do a right signal at all. If there is not someone actually waiting on me before they pull out, I just do my turn. I can turn faster with both hands on the handlebars anyway.