When using the Cocos2D project wizard to create a Cocos2D Mac project, the default window size is usually too small.
To resize it to your needs:
1) Find the .lproj file in your Resources folder (eg. English.lproj)
2) Edit your MainMenu.xib
3) Drag the main window size to your desired size
4) The teapot window is the OpenGL view which contains your game. Resize this as appropriate. (Usually to the size of the entire game window)
If your window is smaller than your content and you need to scale it, see drPedro’s post in this article:
Specifically the setFrameSize calls to scale down the content to fit your window.