Probably could be [rK].

忌ま忌ましい is the form displayed in the majority of references.

@@ -9 +8,0 @@
-<ke_inf>&sK;</ke_inf>

GG5: 〔腹立たしい〕 infuriating; annoying; maddening; irritating; infernal 《noise》; 〔呪わしい〕 hateful; offensive; detestable; (むかつくような) disgusting; revolting.
中辞典: vexing; annoying; aggravating; exasperating; provoking; galling; cursed; confounded; 《文》 vexatious

Terms like "effing' and "frigging" are way off the mark.
See: https://www.edrdg.org/wiki/index.php/Editorial_policy#References
"the Eijiro glossary should not be the sole source of references for a proposed entry, although it may be used as a supplementary reference for confirming meanings. This is because the glossary is a collection of Japanese-English pairs which have apparently been collected from translations. In a Japan Times article Daniel Morales described it as "a smorgasbord of reibun and definitions, some of which err on the side of slang, often delighting the expat community."

@@ -8,0 +9 @@
+<ke_inf>&sK;</ke_inf>
@@ -20,4 +21,5 @@
-<gloss>damned</gloss>
-<gloss>effing</gloss>
-<gloss>infernal</gloss>
-<gloss>frigging</gloss>
+<gloss>infuriating</gloss>
+<gloss>provoking</gloss>
+<gloss>irritating</gloss>
+<gloss>aggravating</gloss>
+<gloss>vexing</gloss>

忌々しい	29225	96.0%
忌ま忌ましい	950	3.1%
忌忌しい	266	0.9%

reordered kanji.
sanoku form is 忌ま忌ましい, oddly enough.

sanoku defines using 腹立たしい (irritating; aggravating; upsetting)

忌忌しい should be low enough for [sK], especially since 忌々しい implies it is a possibility anyway.

Our glosses do not appear in reverso. eow.alc glosses are illumuniting.
https://eow.alc.co.jp/search?q=いまいましい&ref=wl

This appears to be an informal extension of 忌まわしい("to grate on one's nerves"). "damned", "effing" (fucking), are given, along with "cotton-picking" and "consarned".  
Reverso confirms this usage:
A bloody dead man tried to kill me... ("bloody", used in several entries)
Then when that darn levee broke ("darn")
Those darn student loan people start calling
How can I get hold of the ring? Devilish fix! (devilish)
忌々しいビデオを漏らすのを止めるというメッセージ <->  saying "Stop leaking my motherf*king videos",

Seems like a mild expletive expressing irritation. That makes "annoying" and "provoking" more of a definition than a gloss.

Some alternate suggestions: synonyms for "bloody":
https://www.collinsdictionary.com/dictionary/english-thesaurus/bloody
damned (slang) 
flaming 
fucking (taboo, slang) 
bleeding 
blooming (informal) 
freaking (slang, mainly US) 
rotten 
blinking 
confounded 
ruddy 
infernal (informal) 
deuced 
wretched 
frigging (taboo, slang) 

I threw a few of them into the "meanings" just to call attention to the issue. I'm not married to any particular terms. Again, for a considerably longer list of potential glosses:
https://eow.alc.co.jp/search?q=いまいましい&ref=wl

@@ -8 +8 @@
-<keb>忌忌しい</keb>
+<keb>忌ま忌ましい</keb>
@@ -11 +11,2 @@
-<keb>忌ま忌ましい</keb>
+<keb>忌忌しい</keb>
+<ke_inf>&sK;</ke_inf>
@@ -19 +20,4 @@
-<gloss>provoking</gloss>
+<gloss>damned</gloss>
+<gloss>effing</gloss>
+<gloss>infernal</gloss>
+<gloss>frigging</gloss>