I have a skill Double Shot which says that I can lock onto to two enemies with a fully drawn bow and then fire at both simultanously.
However, either I've missed it, or the game doesn't give any instruction on how to lock an enemy. I've checked the Survival Guide and found no answer there.
Best Answer
While you are aiming, zoom in and hover the mouse over a target for a few seconds. You will get the lock-on symbol (a diamond). Then you can move to hover over a second target and you will get a second lock-on symbol, while the first will stay locked on. When you release the trigger, both will be attacked.