Connect a dual output LNB to port A and port B. This will provide horizontal and vertical signals throughout the complete installation. No power injector is required for this multiswitch as the power is provided by the satellite receiver.
The SatKing 2 in 4 out multiswitch enables connection of multiple satellite decoders (up to 4) from a single satellite dish. So, you could run up to 4 separate satellite decoders in different rooms. A twin LNB will be required if you are mixing pay TV decoders and VAST decoders or any service that uses a mix of vertical (13V) and horizontal (18V) signals.