That should depend upon the extent to which tensile strength is required in the base metal accordingly alloying element should be added.. Stress strain curve should help.
I've seen some reports where have used around 30 ppm of Sr for increasing the YS and UTS of 6201 Aluminum alloy. https://link.springer.com/article/10.1007/s11661-997-0265-5
Thanks for the information, Sr is added to modify the eutectic Si phase from plate like structure to fine and fibrous structure, which increases the strength of the alloy. We are facing the problem of drawability during the manufacturing process of conducting wires of 6201 ans 6203 alloy.