Like this, or this, or even more simply than these you could just add protein and fat to reach your desired macro ratios, then reduce the volume of the mix to reach your desired caloric level. After my additions I make 10 days worth out of 5-6 packages of Soylent (depending on the ratio I’m aiming for), doing it this way turns it back into a DIY soylent, but the primary ingredient of which is Soylent. It’s a bit cheaper per day this way too.
I personally am at ~1600kcal/day using Soylent powder/oil, added fat and protein. All of the remaining ingredients in the above links are there to fortify the mix to >100% of the micros, which more recent info has suggested may not be necessary. @MattCauble recently mentioned Soylent may be at 1.5-2x the RDA for the micros, not strictly 100% as the label suggests. Hopefully Rosa Labs will be able to officially acknowledge how much breathing room we may have on the RDA…nudge, nudge.
This may not work for you if you are wanting to stay in keto though. I would expect even the 35/30/35 recipe I linked would kick you out, at least temporarily, but would probably be a bit better than 50% plus carbs from straight Soylent. I have been toying with keto recipes from time to time and was pretty happy with my most recent recipe, it’s not perfect yet though and I’m going to work on it a bit more. I’ve also been happy with just reducing the carbs as above.