The TC40-D will be handled while completing your state return.
As you are working through your Utah return, watch for a page titled "Dependents Who Qualify for Disabled Exemptions". Select 'Yes', then enter the number of dependents on the following screen. Please see attached screenshots below:
Note: If you do not see the screens below, delete the state return and begin again. All information will be transferred directly from your federal return, so there will be no data loss in the state return if you delete it.
https://ttlc.intuit.com/questions/3507397-how-do-i-enter-a-tc-40d
