How to create a percentage-based element that is calculated from the salary basis?

Hi Team,

We are trying to create a non-recurring bonus element that is calculated as a percentage of the base salary amount.
We are not using Oracle Payroll, we only need this element to be used during the hire process, specifically within the employee profile.

Could you please advise on how we can achieve this?
Would it be done by creating a salary basis using rates?

Thanks,

Raven