does Registry.CurrentUser.OpenSubKey create the key if it does not exist?
// No it does not - create it manually on null check
public void ConfigureWindowsRegistry()
{
RegistryKey localMachine = RegistryKey.OpenBaseKey(Microsoft.Win32.RegistryHive.LocalMachine, RegistryView.Registry64); //here you specify where exactly you want your entry
var reg = localMachine.OpenSubKey("Software\\Microsoft\\Office\\Outlook\\FormRegions\\tesssst",true);
if (reg == null)
{
reg = localMachine.CreateSubKey("Software\\Microsoft\\Office\\Outlook\\FormRegions\\tesssst");
}
if (reg.GetValue("someKey") == null)
{
reg.SetValue("someKey", "someValue");
}
}