You want to collect posts from specific influencers to see their performance.
Add influencers from your stream settings:
Go to your stream settings
Click on "selection"
Select the list of your choice
Add influencers with the "move to" button
Click on "move to" (it's often placed in the top right corner of your page or on the top of the dashboard after you select influencer)
Select a stream under "Monitor".
After adding your influencer(s) to your stream, you will see their profile on the "Settings" page of the Monitor function.