I know a lot of people have have had problems commenting on reader because people haven’t setup commenting correctly. But don’t worry, its easy! First of all, if you can’t comment on someone’s shares, they have to fix it. So this guide is written to allow people to comment on your shared items.
Step 1: Click on Sharing Settings
From Google Reader, click on “sharing settings”
Step 2: Select Groups
Google reader uses your contact list and groups from gmail to manage contacts in reader. In order to enable commenting you have to add someone to a group that has commenting enabled. Before we move people into the right group we have to enabled group commenting.
Add People to Groups
You can manage groups through your gmail contact list, or from that same screen click on the people that you’re following and by each of their names will be a groups setting link. That same link is available from the shared page of each person. Add them to a group that has commenting enabled and you’re done!