Below is the script I ended up using. putting the required variables in via scriptlets is what did the trick. i.e. the "<%=fqdn%>"
resWidth = (screen.AvailWidth - 45)
resHeight = (screen.AvailHeight - 150)
MsRdpClient.DesktopWidth = resWidth
MsRdpClient.DesktopHeight = resHeight
MsRdpClient.Width = resWidth
MsRdpClient.Height = resHeight
MsRdpClient.server = "<%=fqdn%>"
MsRdpClient.AdvancedSettings2.RDPPort = "3389"
MsRdpClient.Connect
sub MsRdpClient_OnDisconnected(disconnectCode)
history.go(-1)
end sub