Powershell script- add a "person or group" column with multiple user choice

Hi,

I'm writing a script with Powershell and I'm trying to create a "person or group" column on a custom list, 

but I need the user to select more than one person. (the option of "multiple users" needs to be checked).

right now the code is : 

$list.Fields.Add("Project team", "User", $User)

maybe someone if familiar with the missing attribute?

thanks :) !!