How to display custom field textbox on selection of particular value from the dropdown that created through vCAC property dictionary.

I have displayed a drop-down on VM creation through predefined blue print in vCAC by using  vCAC property dictionary, this drop-down displays the predefined contact person names and last option is others. If user select option others from the drop-down then I want to displays the text-box field to take input from user, how I can do this?

Please suggest is it possible or not, if yes then how.

Thanks