This is a native function of WP and hence the option exists as part of every installation irrespective of the theme used. Can you make sure you check the below option to make the option visible ?
https://docs.google.com/file/d/0B9j6FQo4cSQFUEg2R3pNTzVBVEU/edit?usp=drivesdk
The option should show up at the very bottom of the page edit window; may be that’s why you missed it. Thanks