Walls and Ceilings - patching drywall knock down texture

We removed a whole house attic fan in our hallway and framed in the hole, hung drywall and taped and mudded the edges. Now we are trying to match the knock down texture that the surrounding ceiling has. We bought and are going to try some aerosol spray stuff made to do textured ceilings, but the guy at the hardware store cautioned that most people hadn't had any luck with the spray can stuff. How would you go about doing a small area of knock down texture without a professional sprayer?
Ideas welcome!
Thanks,
Allie

I would trowel on a layer of joint compound, and while it's still wet, dab it with a damp pourous sea foam sponge to try to mimic the surrounding texture.

I always use a hopper gun to spray knock down. I don't know if the aerosol cans spray enough of a splatter to knock it down and resemble your original texture.

I have a friend that used to be in the drywall business and he can use a round brush and dab on some thinned down j/c and then knock it down. I've never had any luck doing it that way except on very minor repairs.

After I've got the field of the patch and the joining perfect I've had good success using a plasterer's dash brush (but you could use a whisk broom) Get the mud the right consistency then dip the brush and use your hand to run across the ends of the bristles to bend them back and let them spring forward and fling some of the mud off. Remember you are not after 100% coveage and the most crucial part of knockdown is the size of the spots and the timing of the knockdown.

I agree with topcoat. This method gets great success in small and large patches. I do ceiling repairs for our local air conditioning company. Feet, knees, and sometimes whole bodies go through the ceilings of houses, and require a patch, and 90% are knockdown. Using the flip brush method after the mud has had a few minutes to set up does great. I also like to use the 20 minute stuff for a quick setup, flip, knockdown, paint. Gets you on to the next job quickly.

Thanks for the suggestions! The aerosol cans didn't work- not enough propellant to get the stuff out of the can, much less splattered on the ceiling?!?!
We got a plastic, manual pump splatter gun thing at Menards (made by Homex I think) and it did a decent job with a lot of my dh's manual labor!
Thanks again,
Allie