Hello Michael,
This feature is already in the latest EasyBlog. However if you only want to files responsible for this they are,
JOOMLA/administrator/components/com_easyblog/controllers/feeds.php
JOOMLA/administrator/components/com_easyblog/views/feeds/tmpl/form_joomla.php
JOOMLA/administrator/components/com_easyblog/views/feeds/tmpl/form_bootstrap.php
JOOMLA/components/com_easyblog/helpers/feeds.php
Please replace the files attached and you will have this fucntionality too
Hope this helps.
Thanks!