RSA eclipse client is unable to show the comments created from design manager web. I am also not able to create comments within the eclipse client. The message shown on the Comments view is "Comments are not supported for the current selection"

What is selected? The Comments view should be enabled for elements selected from the Design Explorer. Alternatively, if you have made a workspace link (usually done automatically) between a model on the server and an element on your workspace, the Comments view should also be active when you select the element from the Project Explorer or diagram. The Comments view will not be enabled for workspace elements where the workspace link has been deleted (or is otherwise not present).

To check whether you have a workspace link, see if the link decorator http://www.ibm.com/developerworks/rational/library/25-server-client-tips/link.gif appears at the root of your model in the Project Explorer. If not, you can add one manually using the Design Explorer's context menu.