Imports System.Runtime.InteropServices.Automation

Public Class OutlookAppointmentHelper
    Const olAppointmentItem As Integer = 1
    Const olMeeting As Integer = 1

    Shared Function CreateOutlookAppointment(ByVal toAddress As String,
                                             ByVal subject As String,
                                             ByVal body As String,
                                             ByVal location As String,
                                             ByVal startDateTime As Date,
                                             ByVal endDateTime As Date) As Boolean
        Dim result = False
        Try
            Dim outlook As Object = Nothing

            If AutomationFactory.IsAvailable Then
                Try
                    'Get the reference to the open Outlook App
                    outlook = AutomationFactory.GetObject("Outlook.Application")

                Catch ex As Exception 'If Outlook isn't open, then an error will be thrown.
                    ' Try to open the application
                    outlook = AutomationFactory.CreateObject("Outlook.Application")
                End Try

                If outlook IsNot Nothing Then
                    'Create the Appointment

                    ' Outlook object model (OM) reference:
                    ' http://msdn.microsoft.com/en-us/library/ff870566.aspx
                    ' Appointment Item members:
                    ' http://msdn.microsoft.com/en-us/library/ff869026.aspx

                    Dim appt = outlook.CreateItem(olAppointmentItem)
                    With appt
                        .Body = body
                        .Subject = subject
                        .Start = startDateTime
                        .End = endDateTime
                        .Location = location
                        .MeetingStatus = olMeeting

                        .Recipients.Add(toAddress)

                        .Save()
                        '.Display()
                        .Send()
                        result = True
                    End With
                End If
            End If

        Catch ex As Exception
            Throw New InvalidOperationException("Failed to create Appointment.", ex)
        End Try
        Return result
    End Function
End Class

Please note that you want to add multiple recipients to the appointment you could pass in an array or List(Of String) and loop through that calling .Add for each one:

Shared Function CreateOutlookAppointment(ByVal toAddress As List(Of String), ...rest of code
.
.
.
Dim appt = outlook.CreateItem(olAppointmentItem)
With appt
    .Body = body
    .Subject = subject
    .Start = startDateTime
    .End = endDateTime
    .Location = location
    .MeetingStatus = olMeeting

    For Each addr In toAddress
        .Recipients.Add(addr)
    Next
    .Save()
    '.Display()
    .Send()
End With

You can also add required attendees by setting appropriate properties. Take a look at the object model for the Appointment item.
Calling Code from a Button on a Screen-
You add a command button to a screen. So here is the code:
Private Sub CreateOutlookAppt_CanExecute(ByRef result As Boolean)

    result = System.Runtime.InteropServices.Automation.AutomationFactory.IsAvailable
End Sub
Private Sub CreateOutlookAppt_Execute()
    ' Schedule the appointment via Outlook
    With Me.Appointment
        If .Customer.Email <> "" Then
            If OutlookAppointmentHelper.CreateOutlookAppointment(.Customer.Email,
                                                                 .Subject,
                                                                 .Notes,
                                                                 .Location,
                                                                 .StartTime,
                                                                 .EndTime) Then
                Me.ShowMessageBox("Appointment has been sent.")
            End If
        Else
            Me.ShowMessageBox("This customer does not have an email address",
                              "Missing Email Address",
                              MessageBoxOption.Ok)
        End If
    End With
End Sub