void AddItemsToRebarContainer(RebarContainer container, FamilyInstance beam, RebarBarType barType, RebarHookType hookType)
{
    // Define the rebar geometry information - Line rebar
    LocationCurve location = beam.Location as LocationCurve;
    XYZ origin = location.Curve.GetEndPoint(0);
    // create rebar along the length of the beam
    XYZ rebarLineEnd = location.Curve.GetEndPoint(1);
    Line line = Line.CreateBound(origin, rebarLineEnd);
    XYZ normal = new XYZ(1, 0, 0);
    Curve rebarLine = line.CreateOffset(0.5, normal);

    // Create the line rebar
    IList<Curve> curves = new List<Curve>();
    curves.Add(rebarLine);

    RebarContainerItem item = container.AppendItemFromCurves(RebarStyle.Standard, barType, hookType, hookType, normal, curves, RebarHookOrientation.Right, RebarHookOrientation.Left,
                                                                true, true);

    if (null != item)
    {
        // set specific layout for new rebar as fixed number, with 10 bars, distribution path length of 1.5'
        // with bars of the bar set on the same side of the rebar plane as indicated by normal
        // and both first and last bar in the set are shown
        item.SetLayoutAsFixedNumber(10, 1.5, true, true, true);
    }

    // Hide the new item in the active view
    container.SetItemHiddenStatus(container.Document.ActiveView, item.ItemIndex, true);
}

Private Sub AddItemsToRebarContainer(container As RebarContainer, beam As FamilyInstance, barType As RebarBarType, hookType As RebarHookType)
    ' Define the rebar geometry information - Line rebar
    Dim location As LocationCurve = TryCast(beam.Location, LocationCurve)
    Dim origin As XYZ = location.Curve.GetEndPoint(0)
    ' create rebar along the length of the beam
    Dim rebarLineEnd As XYZ = location.Curve.GetEndPoint(1)
    Dim line__1 As Line = Line.CreateBound(origin, rebarLineEnd)
    Dim normal As New XYZ(1, 0, 0)
    Dim rebarLine As Curve = line__1.CreateOffset(0.5, normal)

    ' Create the line rebar
    Dim curves As IList(Of Curve) = New List(Of Curve)()
    curves.Add(rebarLine)

    Dim item As RebarContainerItem = container.AppendItemFromCurves(RebarStyle.Standard, barType, hookType, hookType, normal, curves, _
        RebarHookOrientation.Right, RebarHookOrientation.Left, True, True)

    If item IsNot Nothing Then
        ' set specific layout for new rebar as fixed number, with 10 bars, distribution path length of 1.5'
        ' with bars of the bar set on the same side of the rebar plane as indicated by normal
        ' and both first and last bar in the set are shown
        item.SetLayoutAsFixedNumber(10, 1.5, True, True, True)
    End If

    ' Hide the new item in the active view
    container.SetItemHiddenStatus(container.Document.ActiveView, item.ItemIndex, True)
End Sub