DO IT just watermark it using the text took in manga studio. You can change the opacity to make it suitable to your liking.

But seriously. DO IT DO IT DO IT, YOU CAN REALLY DO IT

I agree with Envy go for it the out come is basically learn what you can do to improve that's all there is and sign your art close to the top I usually do that
Not a good look but it keeps the art from being stolen
In all you are a great artist so show em what ya got and even if you don't win just know you did your best and gave it your all

I would say go for it! If you win, great! If not, you can look at the winning piece(s) and see what they did and use it as a learning experience.
Concerning having your work stolen/lost, I read somewhere (and now I try to be better at doing this because I am really terrible at signing my work) to put your signature over the top of the art because it will make it much harder for thieves to erase it. While it unfortunately does make the picture a bit ugly to do that, I would say that it's definitely a safer solution.
Best of luck!!