You can render the report out by declaring an instance of the report viewer and the calling render method (see below)
Dim viewer As New Microsoft.Reporting.WebForms.ReportViewer
Dim sqlReport As Byte()
Dim outMimeType As String = ""
Dim outEncoding As String = ""
Dim outFileExtension As String = ""
Dim outDeviceInfo As String = ""
Dim streamids As String()
Dim warnings As Microsoft.Reporting.WebForms.Warning()
viewer.ProcessingMode = Microsoft.Reporting.WebForms.ProcessingMode.Local
viewer.LocalReport.ReportEmbeddedResource = "MyProjectRootNamespace.MyReport.rdlc"
sqlReport = viewer.LocalReport.Render(format, outDeviceInfo, outMimeType, outEncoding, outFileExtension, streamids, warnings)