Any small scale Colonial, WWI or WWII set of rules will work for the Rif Wars. Check out Colonial Wargames: Rules or Major General Tremorden Rederring’s Colonial-era Wargames Page: Rules for longer lists of Colonial period rules, but choices include . . .
Crossfire / Fuego Cruzado
Disposable Heroes and Coffin for Seven Brothers
Iron Ivan Games has a Rif War supplement for their WW2 rules Disposable Heroes and Coffin for Seven Brothers called Harkas y Arma Blancas: Revised rules for The Rif War 1921-1927. There is also a scenario – “Death by Harka” which is available in the files section on their yahoo discussion group.
Too Fat Lardies
Too Fat Lardies have a variety of offerings for this period. Although not rules, the top of the list is Richard Baber’s wargamer’s guide to the Rif War.
Baber, R. (n.d.). A Wargamer’s Guide to the Rif War. Too Fat Lardies.
I Ain’t Been Shot, Mum
Too Fat Lardies have a Spanish Civil War supplement for IABSM called “Up Your Cara Al Sol”.
Troops, Weapons & Tactics
Too Fat Lardies also have a Spanish Civil War supplement for TW&T called, not suprisingly “Up Your TW&T”.
Charles Grants “Battle” rules
Richard Baber’s group – see Society of Twentieth Century Wargamers (SOTCW) – uses a version of Charles Grants “Battle” rules which he first discovered in about 1976. They have added bits and pieces over the years (stolen from Command Decision & Rapid Fire! among others) for cavalry, aircraft, melee etc. But essentially they are the same rules as published in “Battle – Practical Wargaming”. The rules scale a platoon to 9 figures (we modified this to 9-12 figures); 3 of these platoons for a company (we added a company CP of 4-6 figures too). This gives a company strength on the table top of around 30 – 40 figures, which allows us to play a nice 1:3 scaled game. They have played with actions on the table up to battalion strength with games (mini campaigns) running to Regiment and Brigade size using maps etc. We like the look and feel of these rules; because at this scale you can personalize the game and identify individual figures and during campaigns we have sometimes been able to “awarded medals or promotion” to certain characters which can improve their leadership rating which acts as a modifier Vs morale and in combat to their troops. The rules are not complicated and Richard’s group use them for most periods 1900-1950s after which technology and airpower become too dominant.