In the Registration Template you selected this content should already be implemented. However you may still need to change it to meet your requirements.
1.Click the + to add the Contact Mobile
2.Edit the Label names if you require something different
3.Untick the labels you do not want displayed on the web page
4.Tick the Mandatory tick box if a piece of information is required
5.Enter a Mandatory error validation message if required
If you leave the Drop Down Mode off and do not enter a Drop Down Label the information will follow the previous information e.g. listed on a line on it’s own
If you turn on Drop Down Mode and enter a Label name the mobile information will have a drop down
When you click on the drop down the numbers will open which can be clicked on