Thank you for contacting Telerik Support.
Once you create a custom field, you can define its type, where to be seen, etc. Lets say that you create a custom text field called MyCustomField. Once this field is created and I go to edit the widget template for single news items I will have the ability to add this field to my template, refer to attached image. This will add a field control for my custom field. If this field is not set the field control will not display anything.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items