Here is what I did. All I know is that it works. My receiver is a Yamaha fix-v373.
i run an hdmi cable from the Roku to the hdmi1 slot on the tv. I run a cable from the tv’s hdmi2 to the receivers hdmi1. I solved the sound issue by running an optical cable from the tv to the receiver’s optical port.
On the TV, set the sound to the receiver.