I was trying to get my r2 k2 feed for this kind of work but it will not work. So I decided to see if I can use joomla rss feed.
1. Is there anywhere I can post K2 for both k2 and joomla.
2. automatically post to socials module
3. if any can help me with k2 rss configuration for the category

Hello,

K2 Joomla!"s feed functionality so it is consistent throughout your site.
K2's feeds work the same way as all of Joomla!'s feeds.
If you want to automatically post to social services, take a look at dlvr.it
The settings you are looking for feeds are located in K2's global settings.