None. It's not reportable on Form 5329 at all.
Nonqualified distributions must be reported on Form 8606 Part III, which TurboTax does automatically when you enter the Form 1099-R and you answer the follow-up questions, including those that TurboTax presents after you click the Continue button on the Your 1099-R Entries page, resulting in the calculation of the taxable amount. Since the distribution consists only of original contributions, the result is that none for the distribution is taxable. Since early-distribution penalty's only apply to taxable amounts (other than nonqualified distributions of taxable conversions before the 5-year holding period has been completed), there is no penalty reported on Form 5329 and therefore no need for a penalty exception.
