Using Custom Fonts in iOS project

Hi,

I am wanting to use a custom font in my iOS version of a Xamarin.Forms project. I have been following the blog post on the below link and the author says that I should go in to the info.plist file and tell it where I am storing the font under the Source tab. My problem is that I can't find the Source tab, it just isn't there. Is there something I have to do in order to make it appear?

http://blog.xamarin.com/custom-fonts-in-ios/

Thanks,

Mike.