This is my opinion:
First of all by design there must be only 3 columns. If you need four then it is not easy to be done properly. First you have to change the html, and than the styles in css.
This is quite of a customization.
Here is my advice how you can do it.
what you need to do is to find \Alfresco\Views\Common\Footer.cshtml
In the <div class="footer-lower"> add another div with class for example "security-seal",
right after the <div class="social-sharing">
And after that you need to change the css in Alfresco\Content\css\styles.css
Find the code:
and change it like this
with the next lines you`ll fix the new div
<-- like that you give a little space between the divs
So far is OK, but the there are a few css files for different resolutions that also need to be changed and it gets more complex.
You can try to make it, but it is more tricky indeed.
Hope this helps!
Nop-Templates.com Support Team