It's better to use the function form of the AddPicture method (that is, put
parentheses around the parameter list, and assign the return value to an
InlineShape object representing the inserted picture). That lets you
manipulate the picture's size and any other properties, without having to
resort to the ActiveDocument.Bookmarks("PicA").Range.InlineShapes(1)
expression. Besides that, you can reassign the bookmark to the InlineShape
object's range at the end, so the original bookmark could be collapsed.

Sub foo()
   Dim picRg As Range
   Dim picILS As InlineShape
   Dim picFile As String
   Dim picBookmarkName As String
   Dim picDesiredWidth As Single ' in inches
   Dim picRatio As Single

   picFile = "C:\temp\sample.jpg"

   picBookmarkName = "bk1"  ' change as needed
   picDesiredWidth = 3.2       ' change as needed

   Set picRg = ActiveDocument.Bookmarks(picBookmarkName).Range

   Set picILS = ActiveDocument.InlineShapes.AddPicture( _
        FileName:=picFile, LinkToFile:=False, Range:=picRg)

   With picILS
       ' .LockAspectRatio = msoTrue doesn't work
       ' so you have to do it yourself
       picRatio = CSng(.Height) / CSng(.Width)
       .Width = InchesToPoints(picDesiredWidth)
       .Height = picRatio * .Width
   End With

   ActiveDocument.Bookmarks.Add Name:=picBookmarkName, _
       Range:=picILS.Range
End Sub