SAMP on steam

Install SAMP into the game files downloaded via steam.

Open the location of the game files, do this via Steam or file explorer:
⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀ disk:\Steam\steamapps\common\Grand Theft Auto San Andreas

If you have done so, overwrite the files as follows:

gta-sa.exe → samp.exe
samp.exe → gta-sa.exe
(basically overwrite each other's files).

And now steam tracking your played hours.