I thought I would chime in, since this is kind of my area of expertise.
Beware--extreme linguistic nerdiness follows:
The K sound in English is a kind of sound called a stop (or plosive) that finds it's place of articulation against the soft palette (velum) on the roof of the mouth. It's called a stop because one must stop the air flow from the vocal chords temporarily in order to produce it. The consonant L is a kind of sound called a lateral liquid.
Most English speakers use two kinds of sounds to represent L--one that is more like a vowel for words like love (where L comes first) and one that is more like a stop consonant for words like fell (where L comes last). When we say the word "tickle," we insert a small vowel called a schwa (like the e sound in the word bucket) between the K sound and the L sound. We use the end-type L sound for "tickle."
When we then go on to pronounce tickling, many native English speakers will be confused as to which L sound should be employed, and whether or not they should still insert a schwa between K and L. For my part, I don't believe there is a correct answer for this. Rather, it's a matter of which dialect of English one speaks. There are literally hundreds of dialects of English in America alone, some would say thousands.
According to my dialect, in the case of the word "tickling," I change to the vowel-like L sound and remove the schwa.
/nerdiness
I'd also like to add that doing it is way better than saying it hehe.
