what are the signs of overfeeding?
Belching & bad gas!
Actually, for me it is browning of the leaf/pitcher, or if really overfed, a general decline of the plant itself and possibly even death!
You DON'T want that! So start with less than you think you ought & work your way up in amount, instead of risking poisoning your plant by overfeeding!
For feeding, less is best.... especially in the beginning! For both of you!
To get an understanding of your plants needs, I would suggest you start with one or two pellets at most (for a mature sized plant), & even this recommendation is dependent on the current size of the plant/pitcher. And in the beginning especially, feed no more than 10-20% of the pitchers. That is one (1) out of every 5 to 10 pitchers. For young plants, use less than a full pellet.
I often crush the pellets & hydrate them with water, then take a small amount with a pointy tweezers & drop a tiny amount into the pitchers. This works well for the "infants", but here especially, use a very, very small amount.
Think of the pellets as if they are "potent" bugs. You wouldn't expect the plant to choke down a huge meal!
Especially a high protein/vitamin one!
Good feeding is about providing what the plant is able to metabolize & make use of. In the beginning, most people generally attempt to promote huge & fast growth, which only kills their plants! They also try to feed sick plants or plants suffering from poor conditions, which is even worse.
Feeding a plant is no substitute for giving it the right conditions & environment it needs to be healthy. A plant can't make use of "food" if it isn't under good conditions or in a healthy state. Humidity, temperature, lighting, etc. all affect how much food a plant can make use of. That is why is can be detrimental to a plant to attempt to feed it when it is entering dormancy or even if the temps are too cold or it doesn't get enough light. Under such conditions, feeding it will only encourage rot & death.
So if you understand this concept, as well as how the maturity & size of the plant itself to begin with, can affect how much a plant can "eat", then you will understand that "one size doesn't fit all"!
The best advice is to start with a very small amount, and then be patient to see the plants response over the following few weeks. If it does well, then it may be safe to slightly increase the amount. Always increase in small increments, for "too much" is a lot harder for it to recover from than "not enough"!
It isn't about a "specific amount" of food to use. It is about learning what to do & use in relation to each individual plant. I hope you understand what I am referring to.
Well, that's my opinion & advice. Take it for what its worth.
Good luck.