Just as it is possible to establish subtasks by iterations, it is also feasible to define directly in a task list which resources will be used according to each iteration.
To add resources according to iterations, just add a resource to the task list in the normal way.
Then, when selecting the added resource (it can be an inventory, human resource or service type), an editing bar will be enabled.
When you click on the resource, a new window will appear where you can define in which iterations the resource should be used.
Finally, after making the configuration, click on the save button to make the changes effective.