The correct spelling of the present participle/gerund of 'edit' is 'editing' with one 't'. It seems that you have only learnt half of the rule. You are right that the combination consonant+vowel+consonant needs to double the finial consonant - as in 'hitting' and 'putting' for example - but this only applies when the final syllable is stressed. Peachey actually explained this to you yesterday when you asked about 'gossiping'. For example, if you have a two-syllable word such as 'admit', the stress is on the second syllable. We say 'adMIT' rather than 'ADmit'. This is why the doubling rule applies to this verb, and we spell 'admitting' with a double 't'. In the case of 'edit', however, the stress is on the first syllable - we stress the 'ed' part of the word, not 'it' part of the word. This is why the present participle/gerund is spelt with only one 't' - editing. NB The exception to this rule is verbs ending in 'l', which we spell with a double 'l' in British English. Or you can ignore this exception, if you like, and follow the American convention, which follows the rule.

It's "editing", with a single t. Yes, there is a rule behind this, but it's also just as easy to check a dictionary.

It's "editing" ;-) ¡Saludos!