If you do any any iPhone development, you may run into an issue regarding the text available used in the iPhone buttons. The buttons do not allow you to use superscript or subscript in the text of the buttons. So if you want to do this, you have to create an image that you can then put on the button.

So you'll be left trying to figure out what font to use so that the text in your button looks correct. After much experimentation I can tell you what you want is Helvetica, at 15pt and make it bold. If you do this, your button text will match the button text in the rest of your buttons.

One more trick to get things exactly right, when you are in your program creating the images, set the background color equal to the color used in your buttons. This way the anti-aliasing will match what is used in the other buttons.