Inserting RtkUndiDxe.efi

I have the following Problem.
I have an older FM1 Board Asrock A75 Pro4-M.
Normal oprom updates for this Board are working fine with UBU.
But he Bios has only Realtek PXE oprom, and no undi efi.
So i cant make, uefi network boot.
Normal boot pxe ->ipxe->Wimboot->Http working great. But so i have only MBr mode windows.(other Pc with working uefi network boot runs, fine with W10 uefi network boot)
I try to insert the missing RtkUndiDxe.efi into the Bios, but i do not really know where to start, since i dont know the guid or anything.
Maybe someone can give me an helping hand.

Thx Alex

@jasch :
Hello Alex,
welcome at Win-RAID Forum!

>Here< is the related guide.
Good luck!
Dieter (alias Fernando)