hi i am a player l4d2 but i always using a custom crosshair for playing but we can't see it on obs so do i need any thing for it or its ok ?

You can use a custom crosshair as long as it's achieved through external means (hudsight, mumble, etc) and not a game file edit/addons. If you have any other questions I'd recommend joining the discord server, you'll get answers much quicker https://discordapp.com/invite/ugEWwa5