The Web Service Iterator action is very similar to the Iterators Overview Topic.
Service Page
Configuring the Service details for the action is the same as the Web Service action. See that topic for information.
The only difference is that the "Method" dropdown will only show methods that return arrays of values.
Output Page
The Output page is similar to the output page for the Web Service Action.
If the method returns an array of Primitive types, then a variable is selected to iterate the values of the array.
If the method returns an array of complex types (as shown above), then the iterator will iterate over the values of the array and set each variable to the corresponding field of the complex type. Click on "Read Type Fields" to populate the list of available fields for the method. You do not need to specify a variable for each field, just the fields which you need to read.