Originally Posted by birkey
should there be a matching groove in the rod as well?
No, but to get them to work there needs to be a half round hole on the mating edge of the rod bearing insert that is open to this hole, otherwise their will be no oil flow. These were discontinued a long time ago, modern bearing shells haven't included this feature for many decades.
Unless this is an engine that is going to see very heavy duty use putting an oil stream on the cylinder wall and the bottom of the piston just isn't needed there's plenty of throw-off from the rod journals.
In heavy duty truck and racing applications you still see squirters but these days they tend to be tapped off the main bearing oil supply and directed with a nozzle to the underside of the piston. Some engines use a drilling through the rod shank to direct oil against the piston's underside, found in upscale racing engines and hard working diesels these days.
Using this puts a lot of extra work on the rings as they have to manage the normal throw-off plus this indexed stream, it gets to be a lot of oil. I wouldn't encourage the use unless there is a big need as has been described for heavy duty use or distance racing where the engine runs for long periods of time at high power settings.