THIS MICRO HOW CAN RUN AND WORK
After the For line that sets the folder, try creating the custom field if it doesn't exist - this example adds it to the subfolders - the field needs to already exist in the parent folder.
For i = CurrentFolder.Folders.Count To 1 Step -1
Set olNewFolder = CurrentFolder.Folders(i)
For Each olNewFolder In CurrentFolder.Folders
' replace olNewFolder with the object name you are using for folders.
With olNewFolder.UserDefinedProperties
'On Error Resume Next
Set objProperty = .Add("fieldname1", type, optional format)
Set objProperty = .Add("fieldname2", olDuration)
Set objProperty = .Add("fieldname3", olYesNo, olFormatYesNoYesNo)
End With
Types & formats:
UserDefinedProperty.DisplayFormat Property (Outlook) - if a format is not specified, the default format is used.