What exactly is the RDA? Is this how I should determine if I am getting adequate nutrition?

Answer:
The RDA's (Recommended Dietary Allowances) were first created by the National Research Council in the 1940's to serve as a basis for "good nutrition". Its main use is adequate nutrition in regards to preventing disease, i.e. Scurvy which is caused from a lack of Vitamin C.

The RDAs do not address individual health, or nutrition that is required by "athletes", which really includes anyone that is involved in bodybuilding, weight training or general fitness. So, no I would not advise that you use this as a measure of optimal nutrition.

The following chart is from the ISSA (International Sports Sciences Association) whom I am certified by, that lists the nutritional requirements for 'physically active people'. The PDI is a much more accurate guideline to use for your vitamin, mineral and nutrient requirements.

These PDI values are intended as a guideline for physically active, healthy adults. The PDIs should be obtained from a total nutrition plan, consisting of food and dietary supplements. The PDI ranges for each nutrient reflect the different needs of individuals based on size and activity level. Always consult a health professional with questions on your special nutrition requirements. Table Of Performance Daily Intakes (PDI)
Nutrient	Forms Found In Supplements	PDI
Vitamin A	Vitamin A Acetate, Beta Carotene, Vitamin A Palmitate	5,000 IU to 25,000 IU
Beta Carotene	Beta Carotene	15,000 IU to 80,000 IU
Vitamin D	(D2) Ergocalciferol, (D3) Cholecalciferol	400 IU to 1,000 IU
Vitamin E	Mixed Tocopherols, D-alpha Tocopheryl Succinate,DL-Tocopherols	200 IU to 1,000 IU
Vitamin K	(K1) Phylloquinone, (K2) Menadione	80 mcg to 180 mcg
Vitamin C	Ascorbic Acid, Rose Hips	800 mg to 3,000 mg
Vitamin B1	Thiamine Hydrochloride (HCl)	30 mg to 300 mg
Vitamin B2	Riboflavin	30 mg to 300 mg
Vitamin B3	Niacinamide, Niacin	20 mg to 100 mg
Vitamin B6	Pyridoxine Hydrochloride (HCl)	20 mg to 100 mg
Folate	Folic Acid	400 mcg to 1,200 mcg
Vitamin B12	Cyanocobalamin	12 mcg to 200 mcg
Biotin	Biotin	125 mcg to 300 mcg
Pantothenic Acid	d-calcium pantothenate	25 mg to 200 mg
Calcium	Calcium carbonate, calcium citrate, calcium malate, calcium glycinate	1,200 mg to 2,600 mg
Phosphorus	Phosphorus	800 mg to 1,600 mg
Magnesium	Magnesium oxide, magnesium glycinate	400 mg to 800 mg
Iron	Ferrous (iron) fumarate, Iron glycinate	25 mg to 60 mg
Zinc	Zinc citrate, zinc arginate	15 mg to 60 mg
Iodine	Iodine from kelp	200 mcg to 400 mcg
Selenium	Selenomethionine	100 mcg to 300 mcg
Copper	Copper lysinate, copper gluconate	3 mg to 6 mg
Manganese	Manganese arginate, manganese glycinate, manganese gluconate	15 mg to 45 mg
Chromium	Chromium dinicotinate glycinate, chromium picolinate,	200 mcg to 600 mcg
Molybdenum	Molybdenum chelate	100 mcg to 300 mcg
Sodium	Sodium chloride*	1,500 mg to 4,500 mg
Chloride	Sodium chloride*	1,500 mg to 4,500 mg
Potassium	Potassium chloride	2,500 to 4,000 mg
Boron	Boron tri chelate, boron glycinate, boron citrate	6 mg to 12 mg
Choline	Choline bitartrate, choline dihydrogen citrate, phosphatidyl choline	600 mg to 1,200 mg
Inositol	Myo-inositol	800 mg to 1,200 mg
Bioflavonoids	Citrus, rutin, hesperidin bioflavonoids	200 mg to 2,000 mg
IU=International Units, mg=milligrams, mcg=micrograms		Version 6/2/99
*Sodium and Chloride are derived predominantly from food sources, not dietary supplements.

Credit to the ISSA for this chart.