A simple black frame in wood or metal with a white mat sets off the tones of the black & white image. The width of the mat is one half the width of the print on each side and the top. It is important that the sides and top be the same dimension. The bottom of the mat is slightly deeper to balance the image in the frame, in this case 10% more than the sides and top. This is a typical museum style frame.
The mat window (where the image appears) may be cut so that it slightly covers the edge of the image, or held back so that a small amount of the white border surrounding the image shows. This is a personal preference, mine definitely being the latter as it reveals the entire image, allows the signature to show, and generally appears more generous and relaxed. The amount of border that is left to show may be 1/4" to 3/4" on the top and sides, and slightly more on the bottom if the signature is desired. (In general, the signature is held away from the image to allow the print to be matted in either fashion.)
An alternative is to use a heavier frame with a narrower mat. In this case the dimension of the mat is identical on all four sides.
This is an approach suitable for stronger images where the weight of the frame will not overwhelm the image.
Archival materials must always be used for mounting, matting and framing. It is advisable to use a high quality frame and a heavy, multi-ply mat board. Please ensure that the print is handled with extreme care and that the image surface is never touched.
Again, these recommendations are meant to serve as a reference.
There are many variations that work as well, and the ideal is that which ultimately pleases the owner.