What problem does it solve? Full fine-tuning of 7B-70B language models requires prohibitive GPU memory and produces multi-gigabyte checkpoints. This Skill guides parameter-efficient fine-tuning with LoRA, QLoRA, and 25+ adapter methods so you can train under 1% of parameters on consumer GPUs while keeping accuracy close to full fine-tuning. ## Core Features & Use Cases - LoRA and QLoRA workflows: Configure rank, alpha, dropout, and target modules, with 4-bit quantization to fit a 70B model on a single 24GB GPU. - Adapter management: Load, merge, and switch between multiple trained adapters at runtime for multi-task serving with vLLM. - Advanced variants and troubleshooting: Reference guides cover DoRA, AdaLoRA, LoftQ, rsLoRA, custom module targeting, and fixes for CUDA OOM, NaN loss, and adapter loading errors. - Use Case: Fine-tune Llama 3.1 8B on an instruction dataset with LoRA r=16 on one RTX 4090, producing a 6MB adapter instead of a 16GB checkpoint, then merge it for deployment. ## Quick Start Fine-tune Llama 3.1 8B on my instruction dataset using LoRA with rank 16 and show me how to save and reload the adapter.