Hi Harith

Thank you for reaching out to us.

I'm afraid you don't have this possibility with Amelia custom fields yet.

Here are all custom fields types you can use in your booking form

I'll kindly ask you to add it as a feature suggestion on this page. 

Features are pushed up on our "to-do" list when there are a lot of customers requesting those features, so having your vote as a customer can be beneficial to this feature being developed sooner.