Realband is like that, things that work in every other DAW don't in RB and common things in other DAWs are not in RB.
It is a shame because it is awesome in what it can do, but the interface is so Junior School and behind the times.

Here's an ASIO DirectX you can try
ftp://ftp.steinberg.net/Download/Hardware/ASIO/


Register 32 bit
copy asiodxfd.dll file to C:\Windows\System32

goto C:\Windows\System32 click on cmd.exe

at prompt type RegSvr32 asiodxfd.dll
Restart


Register 64bit
copy asiodxfd.dll file to C:\Windows\SysWOW64

goto C:\Windows\SysWOW64 right click on cmd.exe run as admin

at prompt type RegSvr32 asiodxfd.dll
Restart

You can change Buffer size for delay, just click on it change, hit enter.