radio button checked by default?

I’m trying to set up a “Radio Buttons” field with two options:

field#option1|option1#option2|option2

the user is supposed to choose one of the two options.

Setting the field to “required” doesn’t work – sending the form always leads to an required fields error message, no matter whether there is option chosen or not.

So my intended workaround was to simply pre-select one of the options, hence setting the field to “required” is not necessary as on eof the options is set already and the user can change if he wants.

But I can’t find a way to pre-select one of the radio buttons options. Any idea how to do this?

Thanks and kind regards
Franz

P.S.: I searched for more than an hour and didn’t find anxthing – so please forgive me when this question has been answered before …

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