Step 1
Copy the following code.
Step 2
Log into your Posterous Account.
Step 3
Select your site
Step 4
Click on Theme my site.
Step 5
Select Advanced tab from the left navigation
Step 6
Search for {Body} in the Custom HTML code.
Step 7
Paste your PrintFriendly code after the {Body} div closing tag: </div>
Step 8
Click on Save button.