Hi there,
looking to install a front fence. We liked the idea of white painted timber posts the whole way along with nothing attached like the picture added

looking for guidance on what timber to use. Was thinking of 90x90mm posts but wanted them not to be too rough, do you have to buy Dressed timber? Would h4 pine be ok? Also thought would smaller timber work as well without it getting warped to save on money like 90x45?
any advice would be greatly appreciated. Thank you.