1. It would be nice to have three selection-type options for custom fields: radio button, check box, and drop down list with multi-selection.
1a. Radio Button: requires user to select one option from a (short) list (and they must pick one);
1b. Check Box: allows user to select multiple options from a (short/brief) list; and
1c. Drop Down with multi-selection: allows user to select multiple options from a list (longer more descriptive list than check box).
  1. The current check box option behaves more like a radio button (i.e. only one item that is either selected or not selected), the drop down option also only allows one selection from a list; and there is no radio button option (because the other two do the radio button job).
  2. Its ironic that the "create custom fields" form field-type option of "check box" produces a field that behaves like a radio button, whereas the the form itself uses actual check boxes to pick which reports are to include the field (i.e. allows multiple boxes to be checked (Fees, League, Competitions, etc)).