2016 is an RMD year for your 401(k). A rollover from a 401(k) to an IRA involves a distribution from the 401(k). The first amounts distributed from your 401(k) in an RMD year are deemed to be your RMD until your RMD has been satisfied. Assuming that you meant to say that the distribution from the 401(k) that was rolled over to the IRA occurred in February 2016, not 2015, the portion of the amount moved to the IRA that was 401(k) RMD has already satisfied your RMD, is deemed to be a regular contribution to the IRA, not a rollover, and is now an excess contribution to the IRA and you must request a return of excess contribution of this amount. Since the RMD has already been made, it cannot be deferred to 2017.
See CFR 1.402(c)-2 Q&A 7(a): https://www.law.cornell.edu/cfr/text/26/1.402(c)-2
Some IRA custodians can be a bit uncooperative in helping you make the corrective distribution from the IRA under these circumstances. They must calculate any earnings or loss attributable to the amount of the excess contribution, distribute the adjusted amount, and report the distribution as a returned contribution, not a regular distribution.
How you enter everything into 2016 TurboTax for reporting on your 2016 tax return depends on how the 401(k) administrator reports the distribution that was moved to the IRA and whether the rollover was a direct rollover or an indirect rollover.
