Small belt knives in the less than 4 "range are a very useful and handy piece of equipment. For many campers and backpackers, this is the only fixed blade knife carried in order to hold down weight. If another tool, whether a larger fixed blade , axe, hatchet, tomahawk, machete, is carried for chopping or splitting, then a small fixed blade is all that is needed in the outdoors. If only one knife is carried, my preference is for a slightly larger knife, but many experienced outdoorsmen carry only a small fixed blade with them. It all comes down to personal preference and use. The primary knife jobs tend to be food preparation and fire-building. In average conditions, a small knife can do these tasks easily.
There are many excellent quality small fixed blades that would make great outdoors knives, although there is a bit of overlap between the small and mid-sized fixed blades. The Fallkniven F1 is a very popular and very good quality model. The price is around $ 100, but worth the cost if such a knife is desired. Falkniven's H1 is another option, although not nearly as common. Bark River Knife & Tool (BRKT) makes a number of models that fit this general range. Many of their knives straddle the line between a small and mid-sized fixed blade. The Gunny is a recent model that is similar in size to the Fallkniven, but slightly more expensive. BRKT is not an inexpensive company, but they make excellent knives. The ESEE RC-3 is a great choice for a small hard-use knife at a reasonable price. ESEE makes some of the toughest knives in the business and have a warranty that is unsurpassed. The Rat-3 by Ontario is another option. It was designed by the same people who make the RC-3, and is a good knife, but is made by a different company. Most users prefer the RC-3.
On the other end of the price range, the Frosts Mora Clipper is a great knife at a very cheap price. They are not really meant for heavy use, but they can take a great amount of punishment and keep on going. All Moras actually would be good choices. In the US, the plastic and rubber handled Moras are more popular than the wooden-handled models, but both are quality knives. The Kershaw Antelope Hunter and the Echo are fairly inexpensive, but good quality knives that are not as well known, but have good reputations. Buck makes a few models in this size range that are great choices, especially the Pathfinder. Case and Ka-Bar both also make some small hunting knives that fit the category. Almost every good knife manufacturer offers knives that fit here.