A controversial subject but...
Fertilizing CPs is usually something not recommended for beginners to do. Over-fertilizing will lead to grief. It takes a few years of growing experience to learn the growth habits and the effects of weather and cultivation changes has on those habits. A less experienced grower may not catch the signs of over fertilization before it is too late.
However, Lois fertilizes practically all her greenhouse plants of nearly all genera with a dilute solution of Miracid (as I recall) using a garden sprayer/fogger. I don't recall the strength she said she uses - 10%-25% would be a wild guess. Yes, nearly all genera - Drosera, Cephelotus, Pinguicula, Sarracenia, Nepenthes, and Dionaea - even some Utricularia. Most advise spray only the plants and avoiding as much as possible getting spray/fertilizer on the media.
Osmocote pellets have been successfully used with Sarracenia seedlings (in the medium). The same and fish food pellets or flakes are often feed into pitchers or ground up and sprinkled on sticky traps. A few people use ground up dried insects.
Dilute solutions of Miracid, Alaskan Fish Emulsion, Max Sea and Neptune's Harvest are the brands I've seen discussed as being used successfully with pitcher plants.
Many feel that foliar feeding on the exterior of pitchers to be useless, since the modified organs to absorb nutrients are concentrated in the interior of the pitchers. Perhaps Lois has some observations on this.