If Then statement for Sharepoint Form

I am not sure if I am in the correct forum or not. I have created a form in sharepoint, where if "incurred" is selected in the dropdown field called "rate type" then in my "Rate type elments" field will only show the "Direct" checkbox. If anything other than "incurred" is selected in the drop down, it will show all the checkboxes.

Anyone have any insight on what this code should look like to get this result? Thanks!