Frame.RelativeHorizontalPosition (Word)

Specifies the relative horizontal position of a frame. Possible return values are wdRelativeHorizontalPositionCharacter - Relative to character, wdRelativeHorizontalPositionColumn - Relative to column, wdRelativeHorizontalPositionInnerMarginArea - Relative to inner margin area, wdRelativeHorizontalPositionLeftMarginArea - Relative to left margin, wdRelativeHorizontalPositionMargin - Relative to margin, wdRelativeHorizontalPositionOuterMarginArea - Relative to outer margin area, wdRelativeHorizontalPositionPage - Relative to page, wdRelativeHorizontalPositionRightMarginArea - Relative to right margin.

Set myFrame = ActiveDocument.Frames.Add(Range:=Selection.Range) 
With myFrame 
 .RelativeHorizontalPosition = _ 
 wdRelativeHorizontalPositionMargin 
 .HorizontalPosition = wdFrameRight 
End With