D&F Signature Authority over $1Billion

I think perhaps the President...

I'm not aware that a D&F is required for competitive multiple-award contracts.  A D&F for what?

Leon2015:

If you cite the requirement you may increase your chances at meaningful responses. I, like ji20874 above, am not aware of a FAR requirement for a D&F (see FAR 1.701).

Your agency supplement may have more information as to what is needed and from whom. See also FAR 1.108(f).

The word billion does not appear in the FAR. It appears only five times in the entire FAR System: three times in the DFARS and twice in the DOE supplement. None of those five relate to any D&F for a multiple award IDIQ.