Adobe Photoshop does not have a preset dashed line tool, but that won't keep you from drawing a dashed line rectangle. You just have to be a little more creative and build the dashed line yourself. First you need to create your own custom dashed line brush by modifying an existing square brush. Then, to create a rectangle outlined with a dashed line, draw a rectangular work path and stroke it with your dashed line brush.
Select the "Brush" tool from the Tools palette and open the Brushes palette by either clicking the Brushes palette button in the "Options" bar or choosing "Brushes" from the "Window" menu.
Choose "Square Brushes" from the Brushes palette menu and click the "Append" button to add them to the set of available brushes displayed in the palette.
Click on one of the square brushes. You will create a dashed line brush by modifying a square brush. Choose a square brush that is twice as tall as you want each dash in the line to be. For example, if you want each dash in the line to be 10 pixels high by 20 pixels wide, choose the 20 pixel square brush.
Choose "New Brush Preset" from the Brushes window palette menu. Assign a name to your new brush.
Click on "Brush Tip Shape" on the left side of the Brushes palette. Brush settings appear on the right side of the palette.
Change the Roundness brush setting to 50 per cent. Using 50 per cent for the roundness setting changes the shape of the brush from a square to a dash.
Drag the Spacing slider to the right until the solid line shown in the brush stroke preview becomes a dashed line. Adjust the spacing as desired. The spacing value will be large, as much as 150 per cent or higher.
Click "Shape Dynamics" on the left side of the Brushes palette. Set "Angle Jitter" to 0 per cent and "Angle Control" to "Direction." All other settings should be set to 0 per cent and the associated controls set to Off.
Select the Rectangular Marquee tool from the Tools palette and draw a rectangle.
Right click the mouse and choose "Make Work Path" from the menu that appears.
Open the Paths palette by choosing "Paths" from the Window menu.
Choose "Stroke Path" from the Paths palette menu. The Stroke Path dialogue opens. Choose "Brush" from the drop-down menu and click "OK." The rectangle is drawn with a dashed line.
You may need to tweak your dashed line brush to adjust the appearance of the stroke drawn on a rectangle. Save your dashed line brush to use again later by choosing "Save Brushes" from the Brushes palette menu.