There are good number of examples on loadpull simulations available at AWR MWO installation Examples folder...
Also see the MWO Help menu for step by step procedure for Loadpull Wizard simulations...
AWRDE User Guide > AWR Design Wizards > AWR Load Pull Wizard
9.2. AWR Load Pull Wizard
9.3. AWR Load Pull Script
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Also there is excellent Thesis paper on "DESIGN OF RADIO FREQUENCY POWER AMPLIFIERS FOR HIGH EFFICIENCY AND HIGH LINEARITY" which uses AWR MWO
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I recommend you to go through the same which is similar to what you are doing...