SMS were 65 to 67. There were Uncirculated sets and Proof sets offered by the mint in 64. How to tell the cent of one from the other would probably be the strike. It should be more pronounced on the proof. The uncirculated sets were regular business strike coins. This was my opinion.
Looks like a normal 1964 to me. Whenever someone finds a 1964 Lincoln in reasonably good shape they always think they have one of the 30-50 known SMS coins instead of one of the 2.5 BILLION regular strike Lincoln's.
The easiest way for me (and I suspect for the op) to tell if a 1964 cent is SMS or not is to read what the slab says.
It's pretty easy. First take the photo with the coin filling the screen. Save it to your PC. Then when you post a message, there will be 3 buttons at the bottom right of the window you typing in. The middle button is "Upload a File". Click that button, then follow the instructions. Find the photo you saved and select it. Once it's uploaded, look for a button that says "full size" and select it. Then post the message. Good luck. BTY, if you post it as a thumbnail or if it's cut off or out of focus, the members will tell you all about it. It's all good. Looking forward to your post and photo.
All Lincoln cents minted from 1909 to 1981 were 95% copper and 5% tin and zinc with the exception of the 1943 steel coated zinc. if you’re saying you have a 1964 with an S mint mark, no you don’t. The S mint mark wasn’t used on the Lincoln cent from 1956 through 1967.
There is a big difference between SMS and a SMS Special Strike. You didn’t mention the Special Strike.
Even though a grading company may grade or designate a coin as such there is absolutely no documentation or proof from the mint that these were ever produced as SMS or Special Strike or any other superlative.