Pāṇini sūtras

And the affix ṭak comes after the verb han ‘to kill’ when the object is in composition with it, and when the word to be formed denotes an agent other than a human being.

1. a+manuṣya+kartṛkeअ+मनुष्य+कर्तृके

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   aअ	aअ	aअ	not	aअ
   mम्	manuṣyaमनुष्य	manuṣyaमनुष्य	man	manuṣyमनुष्य् + plus aअ
   kक्	kartṛkaकर्तृक	kartṛkeकर्तृके	agens	kartṛkकर्तृक् + plus eए

2. caच

   Part	Lexeme	Sandhi form	Meaning	Stem
   cच्	caच	caच	besides	caच

Anuvṛtti

1. karmaṇiकर्मणि 3·2·1

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   kक्	karmanकर्मन्	karmaṇiकर्मणि	object	karmकर्म् + plus aṇiअणि

2. hanaḥहनः 3·2·49

   Part	Lexeme	Sandhi form	Meaning	Stem + termination
   hह्	hanहन्	hanaḥहनः	hanहन्	hanहन् + plus aḥअः

3. ṭakटक् 3·2·52

   Part	Lexeme	Sandhi form	Meaning	Stem
   ṭट्	ṭakटक्	ṭakटक्	ṭakटक्	ṭakटक्