Insert Feedburner form Below each post

Hey All,
I am using WPMash thirteen as child theme and twenty thirteen as parent theme for http://www.monkshouts.org .
I want to embed a feedburner subscription box below all posts and pages, the code is available at https://gist.github.com/Wpguide/908a505698df2d14db86 and you can see working it at http://htmledit.squarefree.com/ where you can see HTML code interpretation. I am using a plugin for this task, but rather than using plugin I want to embed this code in my theme so that it can be displayed below the content of all posts. Can anyone tell me the suitable modification where I should put this code in my theme templates?
Thanks & regards,
Vivek Srivastava