First of all, I apologize for the delayed response and thank you so much for the kind words about Criss Cross.
If you are still looking for a solution to this, try the HTML code below:
<a class="ccs-button color-green" title="Button Link" href="#">Button Link <i class="icon-share-2"></i></a>
The code above will create a green button with your text and an icon (from the Criss Cross icon font page) displayed after the text.
Unfortunately, after looking through the icons, I am not sure if there is an “external link” icon included. You may need to use the same instructions but target the icon from an external plugin or stylesheet. Otherwise you are free to use any of the icon classes included with Criss Cross.
Hope this helps.