Nope not on the app I can't but on the web page via safari I do. Did you set your signature via webpage or forum app? I think this makes a difference. I just checked my own signature settings via settings on webpage and went to edit and it doesn't show that I have one. I bet if you put your signature on via the ipad app then it would show up for everyone.
If u look at my screen shot, your signature on main webpage is at bottoms of each of your post under a neat line, ours are all in brackets directly under our text.
(Big Business Game App - Player Name: Beaneys / City Name: kêl)