There are not many specific option F clauses relating to payment so you are back with the core clauses in section 5 of the contract. The only ones that you need to know for option F are the definitions of Defined Cost, Disallowed Cost and the Price for Work Done to Date.
Core clause 50.2 specifically states what the amount due is, which is basically the Price for Work Done to Date (which for option F is 11.2(29)) plus or less other amounts e.g. you can include delay damages if they are already running late, or include amounts if they have achieved any KPI's if they are part of the contract.
Core clause 50.2 specifically states what the amount due is, which is basically the Price for Work Done to Date (which for option F is 11.2(29)) plus or less other amounts e.g. you can include delay damages if they are already running late, or include amounts if they have achieved any KPI's if they are part of the contract.