If R is the gas constant (it should be noted in the source), it is ALWAYS R = 8.314 J/(mol K), even if the units are different for dH and T. You only have to deal with the the units appropriately. If the unit of dH is in some other units, you have to deal with the conversion factors between the units. R is ALWAYS 8.314 J/(mol K). If you change the units, the change of units is compensated for by the change in the numerical factor in front of the units by use of the conversion factors. So R does not change. Please distinguish the numbers which you type in your calculator from the physical quantity.
For T you nearly always should use an absolute temperature.
R is the gas constant and equal to (8.314 J/K.mol). The value of T must be in Kelvin, because you are studying thermodynamic. for more details see this paper:
Article Adsorption of Some Alephatic Dicarboxylic Acids on Zinc Oxid...
The Universal and Individual Gas Constants are known from the Ideal Gas Law.
The Individual Gas Constant - R
The Individual Gas Constant depends on the particular gas and is related to the molecular weight of the gas. The value is independent of temperature. The individual gas constant, R, for a gas can be calculated from the universal gas constant, Ru, and the gas molecular weight, Mgas:
R = Ru/Mgas
In the imperial system,, the most common units for the individual gas constant are ft lb/slug oR. In the SI system the most common units are J/kg K.