From Tmmwiki
You can display radio buttons instead of a select box on the join option
section of the Join Form. Go to Sites Admin, click the Edit Site Templates icon, and replace the old code with the new code, below,
in the template:
Old: Select Box
<select name="signup[optionid]" class="join_select">
{html_options options=$join_options selected=$vars.optionid}
</select>
New: Radio Buttons
For Nats 4
{html_radios name="signup[optionid]" options=$join_options selected=$join_optionids.0 separator="<br>"}
The $join_optionids.0 variable will set the selected radio button to the first option listed.
For Nats 3
{html_radios name="signup[optionid]" options=$join_options selected=$vars.optionid separator="<br>"}
