On my linux server I run the command:
sshpass -p 'password' rsync -avz /source/folder/ root@192.168.x.x:/dest/folder
When I run the command without sshpass it will provide me with prompts for authenticity of host and the password.
I need some equivalent to "-o StrictHostKeyChecking=no" (which I use for ssh) that will allow me to run this with no prompts or errors.
Everything I saw from googling was about ssh throwing the error not rsync.
I found the following command at cyberciti. This allowed me to do exactly what I needed.
$ rsync --rsh="sshpass -p myPassword ssh -o StrictHostKeyChecking=no -l username" server.example.com:/var/www/html/ /backup/