Silicidation of Ta-Ti-Si film on Si (111) and Si (100) substrates was investigated by a new radio frequency (RF) heating in order to evaluate the progress of reaction and establish whether the substrate orientation influence on the rate of reaction prevails. Substrate orientation was observed notwithstanding the high temperatures applied and the very short duration of RF. It was observed that while the reaction on Si (111) goes to completion, on Si (100) substrates under the same conditions intermediate phases remained. A qualitative analysis of the RF treatment of a conductor film on the silicon substrate is presented. It is done for the first time using the mathematical approach of the heat explosion theory. According to the analysis the specimens might experience either heating at constant temperature or by a sudden temperature increase. The relation between the parameters for the heat explosion regime is presented in simple analytical form. Measurable quantities such as sheet resistance and the magnetic field applied determine the stage of the process. The value of the resulting sheet resistance indicates whether the progress of the RF occurred by heating in the slow growth temperature regime or in the heat explosion stage where reactions of a conductor film occur within a fraction of a second.