In Catalog 12.9 (and 14.1 most likely) in the Form Designer open a form with radio buttons, highlight the Radio Button group object. Look at the 3rd pane on the right (I call it the attribute window). You will see an Orientation field, type either "vertical" or "horizontal" in the field and press enter or click on another field to set the change and then click the save button to commit the change. Toggle back and forth as needed between the views to see the difference to setup the look and feel of your form. I also adjust the field set Label Widths to assist with getting everything lined up and looking good in the form.