Final answer:
The correct field used to generate rate card expenses in a financial system is 'Allocate expense'. This term refers to the process of assigning expenses to different services or job roles as per the rate card.
Step-by-step explanation:
In the context of a contract within a financial system or application, the field typically used to generate rate card expenses is most often referred to as Allocate expense.
While 'Distribute expense' and 'Distribute cost' might be related to allocating funds or expenses across different departments or projects, 'Allocate expense' is the term commonly used for assigning expenses to a rate card, which is a document providing the prices for various services or job roles within a company or project.
'Allocate cost' could also be relevant but it usually refers to the distribution of costs rather than the generation of expenses specifically tied to rate cards.