Good Day,

it will difficult to tell you how the calculation will have to setup exactly as I don't know your setup.

You can use Period salary(from Rates and hours )/hours per period which you can type in or refer to the rates and hours field * payslip units capture field for overtime *1.5

I hope this makes sense 

Thank you Kombi. I was able to do this using the Hour per period. Thank you for your response. Really Appreciate