A simple method can be used to convert CLOCK to K4’s MZFPK with the keyword IMPLY.
Take the index of the letter in the plain-text (A->0, B->1, etc) and add the index of the letter in the keyword, then add two. Perform modulo 26 on the result and use that result as an index to get the cipher text.
CLOCK (2, 11, 14, 2, 10)
IMPLY (8, 12, 15, 11, 24)
add:
10, 23, 29, 13, 34
add 2:
12, 25, 31, 15, 36
modulo 26:
12, 25, 5, 15, 10
yields:
MZFPK
Trying the same approach on BERLIN did not yield any useful results for me.