You'll notice in the image above that there is a column called Code. That is the team member's code that will be applied in the field you indicate under the menu item in the image above called "Team Member Tracking".

When a team member places a call to a contact, their code will be set to the field in the Team Member Tracking Setting.

You can then use this value to customize the follow up for a contact by changing the associated user for that contact using the code in a decision diamond or modifying which sequence the contact will be added to next by the team member's code.