In order to investigate the time variations and the peculiarities of the optical spectra of the RV Tauri star R Sct, high-resolution spectroscopic observations in the wavelength interval around the line (6540–6580 Å) were obtained between 2014 and 2018. The phase dependence of the equivalent widths and radial velocities was measured for the and Fe I 5669.224 Å lines, respectively. shows considerable changes in its line profile. We observed double-peaked emission and an inverse P Cygni profile in this line. We detected a variation from inverse P Cygni to P Cygni profile for both Ti I 6554.239 Å and Ca I 6572.797 Å lines at phases where the shock wave is propagating through the atmospheric layer in which the H α lines are forming, particularly around which is just after the deep minimum and , just after shallow minimum. An increase in the shock wave velocity generates a decrease in the intensity, which is explained by the ionization phenomenon. The detailed description of the variations in R Sct reveals its important properties. The observation of the P Cygni and the inverse P Cygni profile indicate that expanding and infalling layers are simultaneously present in the stellar atmosphere, pointing out the complicated nature of this object.