For russian hamsters in general, adult weight should be around 40-60 grams.
I too put the hamster in a carrier and weigh them that way (then weigh the carrier empty. Weight of carrier with hamster - weight of carrier = hamster weight).
I feed my roborovski 10g every 3 days. I don't feed with a bowl, I prefer scatter feeding. Also my ham is pretty chill with me and his hoard so I guess that makes life easier too
I recommend keeping an eye on the hoard, a hamster won't starve themselves and if the hoard is a decent size, you can go a couple of days without adding more food. All hamsters hoard, you just haven't found it yet
