When create a custom field type, I add the dropdown list in the additional column setting to allow user to select a list from my site. How could I write the code to initialize the list of the dropdown list? Please help.
Use a custom control (.ascx) for rendering custom field type UI and add drop-down control inside "RenderingTemplate" control. That way you can handle all events associated with ASCX control. Overwrite CreateChildControls() method to initialize the drop-down control.