How do I cut a hole on a Form?

You haven't specified whether you use Windows Forms or WPF, but because you talk about a "Form", I assume you use Windows Forms.

First, add this to the top of your code file:

Imports System.Drawing.Drawing2D

And to make a hole, do this:

Dim hole As New GraphicsPath()
Dim x As Integer = 0
Dim y As Integer = 0
Dim width As Integer = 100
Dim height As Integer = 100
hole.AddEllipse(x, y, width, height)
Dim formRegion As New Region(New Rectangle(Point.Empty, Me.Size))
formRegion.Exclude(hole)
Me.Region = formRegion

Note that this has a side effect: after setting a value to Me.Region, the style of the form border changes.