You can select the reference style you want from the Style drop down menu in Word. 

If you can't find the style you want, select 'More Styles' from the Style drop down menu. 

Under the 'Get More Styles' tab, search for the name of the style e.g. RMIT University - Harvard. Choose 'Use this Style'. 

Select the 'Installed' tab, select the style you want (should be already installed now).