BTM,
Tou cannot neck size with a fl die, but you can PARTIAL size the neck by backing off the die about 1/4 turn or more.
When you remove the case from the die, you will be able to see the amount of the neck hat has been sized.
Partial sizing works best with cases with longish necks, since it is imperative that you have enough of the neck sized to hold the bullet firmly.
I have partial sized many thousands of rifle cases for use in bolt action rifles over the years, without a tad of trouble.