Vegetable Gardening: Adding vermiculite to existing raised bed

[garden tax](https://imgur.com/a/ml7bbra) (last year before planting)

I ordered soil for my beds last year from a local company and found it to be much too dense. I’d like to add vermiculite to help loosen it up a bit (and as opposed to petite it will also help with water retention in my very dry climate), but I’m not sure the best way to do it.

I know it is generally frowned upon to disturb the soil structure, but do I ignore that this one time and mix it in somehow? Suggestions for doing so? I’ll then be top dressing with compost before planting.

Advice appreciated!