sendKeyToApp.ps1

[void] [System.Reflection.Assembly]::LoadWithPartialName("'Microsoft.VisualBasic")

Start-Process -FilePath 'notepad.exe'

[Microsoft.VisualBasic.Interaction]::AppActivate("Untitled - Notepad")
Start-Sleep -Seconds 2

[System.Windows.Forms.SendKeys]::SendWait("%(fs)")
Start-Sleep -Seconds 2

[System.Windows.Forms.SendKeys]::SendWait("%{F4}")
Start-Sleep -Seconds 2

[System.Windows.Forms.SendKeys]::SendWait("x")