private static extern Int32 RtlInitializeSid([In, Out] ref SID Sid, [In] ref SID_IDENTIFIER_AUTHORITY IdentifierAuthority, byte SubAuthorityCount);

Declare Function RtlInitializeSid Lib "ntdll.dll" (TODO) As TODO

var status = RtlInitializeSid(ref sid, ref id, (byte)sid.SubAuthority.Length);