Word meaning "kicking softly" or "brushing with the feet"?

Scuffing is a good choice here. It means to shuffle or scrape your feet along the ground (Dictionary.com reference). It would indicate reluctance or even some petulance depending on the context, like how a child might shuffle off after being to[ld to go to bed.

Scuffling is a similar word and possibly less harsh sounding (another Dictionary.com reference). I think shuffle is too light for what you want, and if scuff is too heavy, then this is about halfway between a scuff and a shuffle.

"Dusturbing" the sawdust on the floor.

I walked to the wall window, rustling the sawdust on the floor.

Typically used when walking through fallen leaves, I think it sets the right tone if there is a large amount of saw dust. Synonyms in this vein include: stirring, disturbing, raking, swirling, fluttering.

If you want to convey a light covering of sawdust, you could use a term that describes your feet more than the sawdust, such as:

I walked to the wall window, tracking through the sawdust on the floor.

Used in the meaning of

1 a : detectable evidence (as the wake of a ship, a line of footprints, or a wheel rut) that something has passed
    b : a path made by or as if by repeated footfalls : trail

_{Merriam-Webster, track}

Synonyms for this flavor: imprinting, furrowing, gouging, drifting (as in snow drifts), etching.

I suggest Waft:

I walked to the wall window, wafting through the sawdust on the floor.

TheFreeDictionary.com

1. To cause to go gently and smoothly through the air or over water.
2. To convey or send floating through the air or over water.

....

2. the act or an instance of wafting
4. a wafting motion