Two forms 1099-R are required. For the rollover of the Roth 401(k) to a Roth IRA, the plan would report a direct rollover with code H, otherwise the plan would report with code B (possibly with code 1, 2 or 7 depending on your age) a distribution paid to you and subsequently rolled over indirectly within 60 days. For a direct rollover to another qualified retirement plan rather than to a Roth IRA the codes would be B and G together.
For the rollover from the traditional 401(k) the plan would report a direct rollover with code G and would report with code 1, 2 or 7 a distribution paid to you that you rolled over indirectly.
Any indirect rollovers of an offset distribution to pay off an outstanding 401(k) loan after separation from service will include code M (except for an offset distribution from a Roth 401(k) before age 59½).
In TurboTax, simply enter these Forms 1099-R and answer the follow-up questions. For the code G Form 1099-R from the traditional 401(k), simply indicate that it was not rolled over to any kind of Roth account, if that's true. For a code H Form 1099-R, no additional information is needed.