eq: rancilio silvia w/ stock double basket.

for this particular local roast, i am getting good results with approx 14.5g.

it is quite easy when preparing larger doses to have the entire basket filled, swipe across, and tamp down. but with the lower doses, the coffee sits well below the brim. i attempt to smooth it out as much as possible before tamping, but it's never as good as with higher doses. the tamp smooths the puck out nicely and all looks well before pouring, but i continue to get little indentations and small channel-holes (i presume) once the shot is poured and the porta-filter removed from the group head. taste is good, and visually the pour is holding the funnel throughout the entire pour without running as viewed from the naked porta-filter.

is there any particular technique to dosing with smaller amounts of coffee in a standard double basket?

If it tastes good and the pour is behaving, what's the problem? At low doses I have seen similar disturbance in the puck surface, but since the shots tasted and looked fine, it probably happened upon depressurizing since there is more headspace for the coffee to move around.

If you were getting visible channeling, off centered pours, or pin hole spritzing, then their would be a problem. In that case, and/or if you need an easier way to distribute small doses like this, WDT works well since it does not rely on basket volume for even distribution. EDIT: but I do not think this will get rid of your indentations because I believe they are due to depressurization rather than imperfections in the extraction (based on your results). Someone who knows more about puckology can confirm or deny this.

I agree with Johnny about the WDT.

You have a few options.

The easiest way, to WDT it.

Or,
If you want to Stockfleth it, I have posted this in the past: Underdosed Stockfleth - When your dose is below the basket rim. The key is that you lay your finger tip on the rim of the basket and presses the finger down below the rim height, having the bending tip acting as a guide to keep the level equal below the rim. See the pictures there.

Or,
You can use a round plate or the cover of your doser or hopper. Like the Scottie Callaghan dosing tools http://www.scottiecallaghan.com/#!__dos ... -explained

Or,
Don't do any distribution. Dose half your dose into the center. Tap town on the fork. finish dosing into the center. Tamp with your tamper. Don't touch the grounds at all with anything but the tamper at the end. You must go strait down with the tamper. If you want sideways, you ruined it.

The above listed at order of my preference. About equal between 1 and 2 depending on how my loading of the grounds into the basket went.

When downdosing, I'll often give the PF a wack against the palm of my hand to settle and distribute a dose that is mounded in the center. That usually gets things close enough.