Hi Stuart Ray,
As you mentioned, you are using static libraries.
MKL static libraries from which custom libraryis built currently contain all supported CPU-codes. Therefore they are so big in size.
What type of precisions you are looking for DFT transforms?
Do you need both single and double precision DFT transforms?
In case of one precision, you can reduce DLL size by selecting correct names in export list. See comments in DFT example list.