Pickling, sizing, and descaling of Zircaloy with HF leaves firmly bound fluorine on the surface. This deposit can be determined by proton activation utilizing the 19F(p,αγ)16O reaction. The method described herein involves comparing gamma-ray yields from the sample and a comparative standard. The errors inherent in comparing targets of different thicknesses of deposit (hence, different effective cross sections) are calculated. As little as 0.01 µg/cm2 can be determined. The total thickness can be obtained simply. Some results for nuclear reactor components and test coupons are given.