How to use an RCA single speaker post

I was given a pair of HH Scott SH-11 speakers circa 1965 of interest is the back plate's "controlled impedance" toggle switchable to 3 positions hi med low.
The speaker has the typical screw + and common terminals so using them is not a problem BUT it also has an RCA looking jack indicating the outer drain equals common and the pin hole is for +.
My amps have no such output jack. Can you use a bananna for the hot pin but what about the black or - or common part? Any one know this type of conection.
It is still the same positive and negative setup, but with an RCA end as the termination. When I started selling audio gear in the mid '70s, this was a common termination on some of the lower end models. We would just terminate any speaker cable with a RCA connector. Outer ring is negative and inner pin was positive.
That was common on vintage speakers.Some came with complete
systems.The plus most likely will be the same as the red+ on
the banana plug.The RCA plug was on both ends of the cable making it easy for the user when they got the system home .They also use them on a Home Theater In a Box nowadays sometimes.Just ignore the RCA plug.Parts has banana binding post if you end up liking them.Somebody that has some do it yourself skills might be able to put a pair of banana binding post on them permanently. They are generally 3/4"centers standard.Or just use regular speaker wire. Red=+,black=-.If you want to use the RCA for sure,the center will most likely be the red plus.A lot of them don't
make very good connections due to age,and lower quality parts.These parts may be available at Radio Shack stores too.Lesser quality.Most require soldering too.The RCA's usually take only take 18-20gauge wire I hope you get a connection that makes you happy.