Should I partition a database file for performance improvement if a file sits on RAID?

I read a lot about performance improvement if instead of a single large .mdf file you partition it by multiple (.ndf) files. But I also found from documentation that the same improvement can be accomplished if a file created on RAID. So would that make sense for me to partition .mdf file into multiple files or should I just leave it as is, since it's on RAID?