The machines or servers that are exposed in the Distributed Management Console's "Resource Usage: Machine" view are those that host a Splunk instance that is monitored by the DMC.
Therefore, the only way to add a given machine to the scope of that view is for it to host a Splunk instance and to configure the DMC to monitor it.
so, i have 1 indexer , 1 search head and 3 forwarders (that run a full enterprise instance - heavy forwarder). DMC is enabled on the indexer, but the only instance i can see from the drop down menu is the indexer. Can you point me in the right direction ?