I don't recommend O-street for much..other than a pretty picture book. The Pipe Creek are generally somewhat diminutive size, and are often found with arrow points (Edwards, etc). They highly resemble a single notched point, and it's entirely possible they served both functions. While it's stated that some are used as tools (knives), many have been found with impact fractures and other signs of having been used as a projectile. I found a cache of similar (single notched arrow / dart shaped points) a few years back and mistook them for Pipe Creek, but now disagree with my earlier conclusion.
Perino postulates that they could have been used as a fletching tool, but I don't share the same sentiments, as just about any spall could have served that purpose.
To help ascertain what your knife / tool is, you would have to try and figure out what function it was made for. Is it complete? Has it been salvaged? Does it show use wear, and if so, where? Does it have any distinctive manufacturing traits that could help you isolate a certain cultural affiliation? Was it found in any context with other known cultural items? This is the fun part about typology!