Only Simple Pictures (regular shaped artworks) and Video can be framed in Preview. Decals, Cut Outs and Wall Text slots do not have the Frame tab.
There are two approaches to framing:
Adding a simple virtual frame
Load a Simple Picture, go to Frame, and tick Enable Frame. A basic frame will pop up around your picture.
Adjust the shape of the frame by selecting a Frame shape in the Cross Section tab.
The Material tab offers you a choice of materials. Tune the colour of the frame using the Brightness slider.
The Lighting tab allows you to adjust the way light interacts with the surface of the frame. Shine controls the reflectiveness of the material. Metallic tunes the metallic look of the frame. Subtle changes can make a big difference
The Size tab enables you to adjust the depth and width of the frame.
Add Glass by ticking the box at the top.
Framing
2. Recreating an existing frame from a photograph in 3D
The Auto Frame tool is designed to copy frames from photographs in 3D. To use it, you’ll need a cut out image of the frame you want to use saved as a .png with transparency. You can do this in Photoshop (see image on the right for reference).
Load your Simple Picture.
Tick Enable Frame and navigate to the Auto Frame tab.
Select Set up Auto Frame and load the photograph of the frame you wish to use
Line up the edges of the green highlight with the corners of your frame. This is where the picture will appear. You can Zoom in using the mouse wheel for extra precision.
Press Done. You can now tune the profile and dimensions of the frame as before.