The following VBA example creates a rectangle and a linear dimension that is linked to the rectangle's snap points. The dimension value is displayed in decimal format with a leading zero, if necessary.
Sub Test()
Dim shp1 As Shape, shp2 As Shape
Set shp1 = ActiveLayer.CreateRectangle2(0, 0, 5, 2.5)
Set shp2 = ActiveLayer.CreateLinearDimension(cdrDimensionHorizontal, shp1.SnapPoints(1), shp1.SnapPoints(3))
shp2.Dimension.Linear.Style = cdrDimensionStyleDecimal
shp2.Dimension.LeadingZero = True
End Sub