Radio button field types are not currently supported. However, you can achieve a similar effect by using a Checkbox field with icon settings, as outlined in the steps below.
Step 1: Use the "circle" and "dot-circle" icons in the Checkbox field.
Step 2: Set the "circle" option as the Default Value.
If you want to allow users to check only one option in the Subtable, follow the steps below:
Step 1: Add a Numeric field and apply the COUNTIF() formulas to count how many "dot-circle" options are selected in the Subtable.
Example: COUNTIF(A7, "dot-circle")
Note: You can hide this field if needed.
Step 2: Apply Validation as "1" in the Numeric field, which means the record can only be saved when exactly one option is selected.
Note: You can also add an error message. If users select more than one option, an error will be shown when saving the record.