Set slow cooker to high and melt butter, or microwave and pour inside pot. Pour rice into a strainer and run water over it to rinse. Shake off to let the excess water drip off. Pour into pot.
Stir with butter, cover and allow to sit for 10 minutes on the high setting.
Stir in broth and salt. Recover and cook on high for 2.5 hours. Fluff with a fork and serve.