Alright, I've figured out the situation.
The molar ratio is 1:1, a mole of 5-meo-dmt weights 218.3 g/mol while a mole of HCl is 36.5 g/mol.
So a mole of the salt would be 254.8 g/mol
To see the proportion, just need to make 218.3 : 254.8 = Y : X
where Y is the desired freebase amount.
more or less, we can also make 1 : 1.2 = Y: X
in simple terms, we need to moltiplicate the desired amount of fb per 1.17 to obtain the salt needed.
(like, for 12 mg fb, we make 12*1.17 = 14.04)
thanks for answering, hope this helps you =)