As you may already know you know promote some link or document as best bet for a search results (Search keyword and Fast Search Keyword.
BUT, if your search center (SharePoint or Fast) is independent; meaning located in other web application (search search.hametbenoit.info), managed keyword will not be used for promoting your Best bet. Indeed, the scope for keywords is limited to the site collection.
When I wanted to implement this feature with my Fast environment, I discovered that the Fast Search feature were not available through the Site Settings (Site Actions\Site Settings\Site collection administration).
As there is no ‘manageable Fast features’ (meaning no link available through the Site Settings\Site collection features), I looked for enabling it using PowerShell (Get-SPFeature | Where {$_.DisplayName -like "*search*"})
As result
DisplayName Id Scope
———– – —–
OSSSearchEndUserHelpFeature 03b0a3dc-93dd-4c68-943e-7ec56e65ed4d Site
OSearchHealthReportsPushdown 09fe98f3-3324-4747-97e5-916a28a0c6c0 Farm
SearchAndProcess 1dbf6063-d809-45ea-9203-d3ba4a64f86d WebA…
SPSearchFeature 2ac1da39-c101-475c-8601-122bc36e3d67 WebA…
OSearchEnhancedFeature 4750c984-7721-4feb-be61-c660c6190d43 WebA…
SearchExtensions 5eac763d-fbf5-4d6f-a76b-eded7dd7b0a5 Site
OSSSearchSearchCenterUrlSit… 7ac8cc56-d28e-41f5-ad04-d95109eb987a Site
OSSSearchSearchCenterUrlFea… 7acfcb9d-8e8f-4979-af7e-8aed7e95245e Web
OSearchBasicFeature bc29e863-ae07-4674-bd83-2c6d0aa5623f WebA…
SearchAdminWebParts c65861fa-b025-4634-ab26-22a23e49808f Web
OSearchCentralAdminLinks c922c106-7d0a-4377-a668-7f13d52cb80f Farm
SearchServerWizardFeature e09cefae-2ada-4a1d-aee6-8a8398215905 Site
OSearchHealthReports e792e296-5d7f-47c7-9dfa-52eae2104c3b Site
SearchWebParts eaf6a128-0482-4f71-9a2f-b1c650680e77 Site
OSearchPortalAdminLinks edf48246-e4ee-4638-9eed-ef3d0aee7597 Farm
So, the Fast feature GUID is 5EAC763D-FBF5-4d6f-A76B-EDED7DD7B0A5.
Then to enable the feature on your site (this is also applicable for ‘non search center’ template site, in case of this feature is missing), open a PowerShell command and run
$site = get-SPSite <URL of your site collection>
$site.Features.Add(“5EAC763D-FBF5-4d6f-A76B-EDED7DD7B0A5″)
Et voilà, I was then able to add Fast keyword on my Fast search center.