I've used 12oz. of Amaretto in 5 gallons of coffee stout and the Amaretto flavor was noticeable, but not overpowering. I imagine a pale ale would need less. Amaretto has residual sugar that will ferment out, so it isn't something you can add at bottling time. Same goes for Orgeat, but that has even more sugar.
Another option is Almond extract commonly used in baking which is also made from bitter almonds. You could add it to your bottling bucket until you get the amount of flavor you want. I haven't tried that, but you wouldn't need much of it. You could add it in 1/2 teaspoon increments. I doubt you would need more than a couple teaspoons.
If you want to try regular almonds, go for it. I've never used them. I've tried a few commercial beers that use almonds and none of them had a noticeable almond flavor.