You can make sure that the users do not have to do the dot-sourcing by placing that line in the profile.
That way the function is loaded automatically when the PowerShell session starts.
And you can also look at creating a module, that way you store all your functions together.
And provided you don't explictely skip the load of modules, the functions will be known as well.
The advantage is you don't have to include all the dot-sourcing lines in one of the profile files.