From what I could find with a quick look,
On 6 April 43, a battery of 7 SIG 33B were assigned to 23 PD and incorporated into Pz.Rgt. 201 as 9.(StuIG)/Pz.Rgt 201. In noting that III./Pz Rgt 201 had been dissolved on 5 March 43, 9.(StuIG)/Pz.Rgt 201 was assigned to Stab/Pz.Rgt 201.
The Sig33B attached to Pz.Rgt 201 were never at Kursk or Kharkov. Pz.Rgt 201 remained attached to 23 PD throughout the Kursk and Kharkov period and while 23 PD was with H.Gr. Sud it remained much further to the south.
For the Kursk period 23 PD appear to have spent the entire time in transit.
On 2 July they were refitting NE of Donetsk. Then on 3 July they were ordered to transfer to Merefa, just south of Kharkov and completed the move by the 11th.
On the 13th they were ordered to move back to the south and by the 17th they were deployed near Artemivsk, 50 Kms north of Donetsk.
For the Kharkov period;
On 10 Aug, 23 PD are in reserve near Barvinkove and then only on 16 Aug are they transferred to the front and commited near Dolyna.
Both locations are about 20 Kms south of Izyum and about 100 Kms south of Kharkov.
There are some mentions of them causing heavy losses on 27 July and the 6th of Oct 43 using open sights on inf but for an exotic Panzer within a Panzer division there is surprisingly little.
There is also no direct mention of them in the monthly condition reports from 23 PD for the period they were assigned to the unit.
There are no Stugs listed with the unit till 1 June 44, nor does the PzIII list seem to show them.
Sometime in the spring of 44, 9./Pz.Rgt 23 ceased to exist showing that the last of the SIG 33B had been lost by this time.
Stu.Pz.Abt 216 is a separate unit and very well covered on Richards Strumpanzer site.
Sources; (because the authors should get the credit).
Fire Brigades. K.Nevenkin
23 PD History E.Rebentisch
PzTrpn 2 T.Jentz