class Log {
    [string]$path

    # Constructor
    Log ([string] $path) {  $this.path = $path }

    [void] info ([String] $message) {
        Write-Host $message
        $message | Add-Content -Path $this.path -EA Stop
    }

}

$block = {
    foreach ($y in 1..100) {
        ($using:log).info("Logging from RSJob.  Test #$y")
    }
}

Try {
    $log = [Log]::New("$PSScriptRoot\test.txt")
    foreach($x in 1..100) {
        $log.info("Logging from Main function.  Test #$x")
    }
    Start-RSJob -Name "job1" -ScriptBlock $block
    While ($true) {
        start-sleep 1
    }

}
Finally {
    Get-RSJob -Name "job1" | Remove-RSJob -Force
}