Selecting Keyboards

I apologize in advance for what may be a foolish question but I was wondering if there was a way to add a “Done”/”Return” key to the Number Pad. The application I’m currently working on has a textField that only needs to accept numbers. While I could and am currently using the Numbers and Punctuation keyboard I would like to trim the fat (In this case, all the punctuation symbols). I know the Authors took about a page to say how important it is to use the proper keyboard and I’d like to follow their advice (pg 35).

Any help would be appreciated, Thanks!