uses RichEdit;

function RTFtoBitmap(myRTF: TRichEdit; GiveSpaceForBorder: Integer): TBitmap;

var
  myRect: TRect;
  temp: TBitmap;
begin
  temp := TBitmap.Create;

  myRect := myRTF.ClientRect;
  // using this statement
  // myRect := Rect(0,0,MyRTF.Width,MyRTF.Height);

  temp.Width  := myRect.Right;
  temp.Height := myRect.Bottom;
  with temp.Canvas do
  begin 
    Lock; 
    try
      myRTF.Perform(WM_PRINT, Handle, PRF_CLIENT);
      //you can trying to change PRF_CLIENT with
      //PRF_CHILDREN or PRF_CLIENT or PRF_NONCLIENT or PRF_ERASEBKGND
      //or combine them. See what happen...
    finally
      Unlock
    end;
  end;
  Result := TBitmap.Create;
  Result := CreateEmptyBmp(clWhite,
    temp.Width + GiveSpaceForBorder * 2,
    temp.Height + GiveSpaceForBorder * 2);
  Result.Canvas.Lock;
  Result.Canvas.Draw(GiveSpaceForBorder, GiveSpaceForBorder, temp);
  Result.Canvas.Unlock;
  temp.Free;
end;

procedure MakeBorder(const bdr: TBitmap; BorderWidth: Integer; BorderColor: TColor);
begin
  with bdr.Canvas do
  begin
    Brush.Style := bsClear;
    pen.Width := BorderWidth;
    pen.Color := BorderColor;
    rectangle(BorderWidth - 1, BorderWidth - 1, bdr.Width, bdr.Height);
  end;
end;