Flams are separate sounds in PolyNome.
Flam sounds are available for snare, practice pad, and voice.
You assign the flam sound to R, L, K or H in the Change Sounds page.
Tap and hold one of the buttons to bring up the sound picker, then search for 'flam' to see the options.
Flams will show up in the sticking as rL (for left flam) and lR (for right flam)
For rudiment entry, assign a right flam to K, and a left flam to H. Then you can program a flam-a-diddle with the letters: K L R R H R L L