Only wanted to use 1/2" because I have it already.
Is this the set you used? I see a few different ones from Freud
I did mine using this set on a router table:
Freud 1-3/4" (Dia.) Adjustable Tongue & Groove Bit Set with 1/2" Shank (99-036) https://www.amazon.com/dp/B00006XMTT/ref=cm_sw_r_cp_api_glt_fabc_D3E94Z5WZXVBYDMTN565
Once I routed the groove I then made a few passes and adjustments using scrap to get the right fit and then routed the tongue on the rails.
https://www.amazon.com/Freud-Adjustable-Tongue-Groove-99-036/dp/B00006XMTT Maybe this helps ?
One of the easiest and most accurate ways to do them is with a router bit set like this one: