Sizer is a freeware application developed by a third party for MS Windows operating systems.It is not applicable to MAC or any other operating systems.
For general information and FAQs about Sizer Click Here
Set it to startup with Windows.
If
the right click context menu does not appear in Chrome or Firefox
windows (which can occur in Windows 10), the default keyboard shortcut
(Ctrl + Win + Z) works fine, or you can make your own in the
configuration dialog.