That old question: do we frame an oil painting under glass?
Definitely not! Oil and acrylic paintings shouldn't be framed under glass. Their varnish is protection enough. Some authorities even caution against cardboard on the back of the stretcher strips, saying the canvas needs room to breathe and completely dry. The drying process takes many years, even though it feels dry to the touch.
A frame for an oil painting doesn't have to be heavy and sturdy. Although we do want a good frame, it doesn't have to support a lot of weight like a watercolor with glass.
To order a frame, you need to measure the outside diminsions of the oil painting. A canvas 16" x 20" will need a frame of that exact size. No mats are used on oil paintings so it's simple to measure and order.
This a good example of a unobtrusive frame. It will not detract from any painting reguardless of the subject matter.
Don't overframe! The more ornate the frame, the less the painting will be noticed. The frame must add to the overall look and not detract by being so noticeable.
Any remember to hang your art work away from nicotine sources! Nicotine from just average smoking, will stain a painting and its frame in a very short time.
You can save money by framing your own oil paintings. Purchasing from ebay frame sellers is easy and cheaper than buying from a frame shop.