How to adjust the WinForms Docking Manager control size based on the parent form size?

//Initialize the size
Size minimumsize = new Size(200, 200);
void Form1_Resize(object sender, EventArgs e)
{
    //Set the minimum size for the docked control
    this.dockingManager1.SetControlSize(this.panel1, minimumsize);
    this.dockingManager1.SetControlSize(this.panel2, minimumsize);
}

'Initialize the size
Private dock_MinimumSize As New Size(200, 200)
Private Sub Form1_Resize(ByVal sender As Object, ByVal e As EventArgs)
    'Set the minimum size for the docked control
    Me.dockingManager1.SetControlSize(Me.panel1, dock_MinimumSize)
    Me.dockingManager1.SetControlSize(Me.panel2, dock_MinimumSize)
End Sub