ASTM D323 - 15a Standard Test Method for Vapor Pressure of Petroleum Products (Reid Method) describes how to to determine the vapor pressure at 37.8 °C (100 °F) of petroleum products and crude oils with initial boiling point above 0 °C (32 °F),
if you know the composition you can simulate Reid Test and calculate the Reid Vapor Pressure which is slightly different from the True Vapor Pressure (the bubble point of the mixture) , many simulators includes procedures for estimating the Reid vapor Pressure, for example my copy of Prode Properties includes the method StrRVP() exported in Excel as macro which returns the Reid Vapor Pressure calculated according D6377 (liquid not saturaed with air) or D323 (liquid saturated with air) ,
as said you can calculate the True Vapor Pressure (bubble point) which normally is not too different from RVP...