Using custom comments in Astroid Framework

In Order to add custom comment section (eg. k2) you can select custom comment option in Template Settings -> Astroid Template Options -> Article/Blog Options -> Single Article Options -> Comments -> Custom

And create default_comments.php file on below location

JOOMLA_ROOT/templates/YOUR_TEMPLATE/html/frontend/blog/modules/default_comments.php

You can place your code here. Article object can be access as $displayData['article']